Attachment 438943 Details for Bug 230551 – Patch

[patch] Patch

wd-update-tests.diff (text/plain), 716.67 KB, created by Carlos Garcia Campos on 2021-09-22 06:14:14 PDT

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Filename:

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Creator: Carlos Garcia Campos

Created: 2021-09-22 06:14:14 PDT

Size: 716.67 KB

patch

obsolete

>diff --git a/Tools/ChangeLog b/Tools/ChangeLog
>index 18856cda3fb8..ab1cee0e73a2 100644
>--- a/Tools/ChangeLog
>+++ b/Tools/ChangeLog
>@@ -1,3 +1,25 @@
>+2021-09-22  Carlos Garcia Campos  <cgarcia@igalia.com>
>+
>+        [WebDriver] Update w3c and selenium tests
>+        https://bugs.webkit.org/show_bug.cgi?id=230551
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        * Scripts/run-webdriver-tests: Run with python3
>+        * Scripts/webkitpy/__init__.py: Use a newer version of pytest and its dependencies to match what tests expect.
>+        * Scripts/webkitpy/webdriver_tests/pytest_runner.py:
>+        (collect): Use contextlib to redirect stdout to /dev/null while collecting tests.
>+        (run): Use ExitCode new enum added to pytest.
>+        * Scripts/webkitpy/webdriver_tests/webdriver_selenium_executor.py:
>+        (WebDriverSeleniumExecutor.__init__): Do not encode paths.
>+        * Scripts/webkitpy/webdriver_tests/webdriver_test_runner_selenium.py:
>+        (WebDriverTestRunnerSelenium.collect_tests): Use items() instead of iteritems() that doesn't exist in python3.
>+        * Scripts/webkitpy/webdriver_tests/webdriver_w3c_executor.py:
>+        (WebKitDriverServer.__init__):
>+        (WebDriverW3CExecutor.__init__):
>+        (WebDriverW3CExecutor.setup):
>+        (WebDriverW3CExecutor._runner):
>+
> 2021-09-22  Carlos Garcia Campos  <cgarcia@igalia.com>
> 
>         REGRESSION(r282082): [GTK] Tests timeout when using xvfb after r282082
>diff --git a/Tools/Scripts/run-webdriver-tests b/Tools/Scripts/run-webdriver-tests
>index f49174963f8e..e246843453fa 100755
>--- a/Tools/Scripts/run-webdriver-tests
>+++ b/Tools/Scripts/run-webdriver-tests
>@@ -1,4 +1,4 @@
>-#!/usr/bin/env python
>+#!/usr/bin/env python3
> 
> # Copyright (C) 2017 Igalia S.L.
> #
>diff --git a/Tools/Scripts/webkitpy/__init__.py b/Tools/Scripts/webkitpy/__init__.py
>index eb680e5a489c..1768e886b5dc 100644
>--- a/Tools/Scripts/webkitpy/__init__.py
>+++ b/Tools/Scripts/webkitpy/__init__.py
>@@ -53,16 +53,17 @@ AutoInstall.register(Package('funcsigs', Version(1, 0, 2)))
> AutoInstall.register(Package('importlib_metadata', Version(1, 7, 0)))
> AutoInstall.register(Package('genshi', Version(0, 7, 3), pypi_name='Genshi'))
> AutoInstall.register(Package('html5lib', Version(1, 1)))
>+AutoInstall.register(Package('iniconfig', Version(1, 1, 1)))
> AutoInstall.register(Package('mechanize', Version(0, 4, 5)))
> AutoInstall.register(Package('more_itertools', Version(4, 2, 0), pypi_name='more-itertools'))
>-AutoInstall.register(Package('mozprocess', Version(1, 2, 0)))
>-AutoInstall.register(Package('mozlog', Version(6, 1)))
>+AutoInstall.register(Package('mozprocess', Version(1, 3, 0)))
>+AutoInstall.register(Package('mozlog', Version(7, 1, 0), wheel=True))
> AutoInstall.register(Package('mozterm', Version(1, 0, 0)))
>-AutoInstall.register(Package('pluggy', Version(0, 5, 2)))
>+AutoInstall.register(Package('pluggy', Version(0, 13, 1)))
> AutoInstall.register(Package('py', Version(1, 5, 2)))
>+AutoInstall.register(Package('pytest_asyncio', Version(0, 14), pypi_name='pytest-asyncio'))
> AutoInstall.register(Package('pytest_timeout', Version(1, 4, 2), pypi_name='pytest-timeout'))
>-# Pytest held to 3.x due to WPT webdriver compatibility
>-AutoInstall.register(Package('pytest', Version(3, 6, 2), implicit_deps=['pytest_timeout']))
>+AutoInstall.register(Package('pytest', Version(6, 1, 2), implicit_deps=['pytest_asyncio', 'pytest_timeout']))
> AutoInstall.register(Package('pycodestyle', Version(2, 5, 0)))
> AutoInstall.register(Package('scandir', Version(1, 10, 0)))
> AutoInstall.register(Package('soupsieve', Version(1, 9, 6)))
>@@ -70,6 +71,7 @@ AutoInstall.register(Package('selenium', Version(3, 141, 0)))
> AutoInstall.register(Package('toml', Version(0, 10, 1)))
> AutoInstall.register(Package('wcwidth', Version(0, 2, 5)))
> AutoInstall.register(Package('webencodings', Version(0, 5, 1)))
>+AutoInstall.register(Package('websockets', Version(8, 1)))
> AutoInstall.register(Package('zipp', Version(1, 2, 0)))
> AutoInstall.register(Package('zope.interface', Version(5, 1, 0), aliases=['zope'], pypi_name='zope-interface'))
> 
>diff --git a/Tools/Scripts/webkitpy/webdriver_tests/pytest_runner.py b/Tools/Scripts/webkitpy/webdriver_tests/pytest_runner.py
>index 0ec65f94bfac..f1e4148522b1 100644
>--- a/Tools/Scripts/webkitpy/webdriver_tests/pytest_runner.py
>+++ b/Tools/Scripts/webkitpy/webdriver_tests/pytest_runner.py
>@@ -20,6 +20,7 @@
> # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
> # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> 
>+import contextlib
> import errno
> import os
> import shutil
>@@ -29,7 +30,7 @@ import tempfile
> from webkitpy.common.system.filesystem import FileSystem
> from webkitpy.common.webkit_finder import WebKitFinder
> import pytest
>-from _pytest.main import EXIT_INTERNALERROR
>+from _pytest.config import ExitCode
> 
> 
> class TemporaryDirectory(object):
>@@ -168,16 +169,14 @@ class TestExpectationsMarker(object):
> 
> def collect(directory, args, ignore_param=None):
>     collect_recorder = CollectRecorder(ignore_param)
>-    stdout = sys.stdout
>-    with open(os.devnull, 'wb') as devnull:
>-        sys.stdout = devnull
>-        with TemporaryDirectory() as cache_directory:
>-            cmd = ['--collect-only',
>-                   '--basetemp=%s' % cache_directory]
>-            cmd.extend(args)
>-            cmd.append(directory)
>-            pytest.main(cmd, plugins=[collect_recorder])
>-    sys.stdout = stdout
>+    with open(os.devnull, 'w') as f:
>+        with contextlib.redirect_stdout(f):
>+            with TemporaryDirectory() as cache_directory:
>+                cmd = ['--collect-only',
>+                       '--basetemp', cache_directory]
>+                cmd.extend(args)
>+                cmd.append(directory)
>+                pytest.main(cmd, plugins=[collect_recorder])
>     return collect_recorder.tests
> 
> 
>@@ -192,16 +191,16 @@ def run(path, args, timeout, env, expectations, ignore_param=None):
>     with TemporaryDirectory() as cache_directory:
>         try:
>             cmd = ['-vv',
>-                   '--capture=no',
>-                   '--basetemp=%s' % cache_directory,
>+                   '--capture', 'no',
>+                   '--basetemp', cache_directory,
>                    '--showlocals',
>-                   '--timeout=%s' % timeout,
>+                   '--timeout', str(timeout),
>                    '-p', 'no:cacheprovider']
>             cmd.extend(args)
>             cmd.append(path)
>             result = pytest.main(cmd, plugins=[harness_recorder, subtests_recorder, expectations_marker])
> 
>-            if result == EXIT_INTERNALERROR:
>+            if result == ExitCode.INTERNAL_ERROR:
>                 harness_recorder.outcome = ('ERROR', None)
>         except Exception as e:
>             harness_recorder.outcome = ('ERROR', str(e))
>diff --git a/Tools/Scripts/webkitpy/webdriver_tests/webdriver_selenium_executor.py b/Tools/Scripts/webkitpy/webdriver_tests/webdriver_selenium_executor.py
>index fbd7626f559e..5e57483da624 100644
>--- a/Tools/Scripts/webkitpy/webdriver_tests/webdriver_selenium_executor.py
>+++ b/Tools/Scripts/webkitpy/webdriver_tests/webdriver_selenium_executor.py
>@@ -40,8 +40,8 @@ class WebDriverSeleniumExecutor(object):
>         self._env = env
>         self._env.update(driver.browser_env())
> 
>-        self._args = ['--driver=%s' % self._driver_name, '--driver-binary=%s' % driver.binary_path().encode()]
>-        browser_path = driver.browser_path().encode()
>+        self._args = ['--driver=%s' % self._driver_name, '--driver-binary=%s' % driver.binary_path()]
>+        browser_path = driver.browser_path()
>         if browser_path:
>             self._args.extend(['--browser-binary=%s' % browser_path])
>         browser_args = driver.browser_args()
>diff --git a/Tools/Scripts/webkitpy/webdriver_tests/webdriver_test_runner_selenium.py b/Tools/Scripts/webkitpy/webdriver_tests/webdriver_test_runner_selenium.py
>index b0beea0f9142..06512e4fd76f 100644
>--- a/Tools/Scripts/webkitpy/webdriver_tests/webdriver_test_runner_selenium.py
>+++ b/Tools/Scripts/webkitpy/webdriver_tests/webdriver_test_runner_selenium.py
>@@ -50,7 +50,7 @@ class WebDriverTestRunnerSelenium(object):
>         # Collected tests are relative to test directory.
>         base_dir = os.path.join(self._tests_dir, os.path.dirname(relative_tests_dir))
>         collected_tests = {}
>-        for test, subtests in executor.collect(os.path.join(self._tests_dir, relative_tests_dir)).iteritems():
>+        for test, subtests in executor.collect(os.path.join(self._tests_dir, relative_tests_dir)).items():
>             collected_tests[os.path.join(base_dir, test)] = subtests
>         selenium_tests = []
>         if not tests:
>diff --git a/Tools/Scripts/webkitpy/webdriver_tests/webdriver_w3c_executor.py b/Tools/Scripts/webkitpy/webdriver_tests/webdriver_w3c_executor.py
>index cc2d075bc0af..1843de553779 100644
>--- a/Tools/Scripts/webkitpy/webdriver_tests/webdriver_w3c_executor.py
>+++ b/Tools/Scripts/webkitpy/webdriver_tests/webdriver_w3c_executor.py
>@@ -115,8 +115,8 @@ class WebKitDriverServer(WebDriverServer):
>     default_base_path = '/'
>     test_env = None
> 
>-    def __init__(self, logger, binary=None, port=None, base_path='', args=None):
>-        WebDriverServer.__init__(self, logger, binary, port=port, base_path=base_path, args=args, env=self.test_env)
>+    def __init__(self, logger, binary=None, port=None, base_path='', env=None, args=None):
>+        WebDriverServer.__init__(self, logger, binary, port=port, base_path=base_path, env=self.test_env, args=args)
> 
>     def make_command(self):
>         return [self.binary, '--port=%s' % str(self.port)] + self._args
>@@ -135,8 +135,8 @@ class WebDriverW3CExecutor(WdspecExecutor):
>         server_config = {'browser_host': server.host(),
>                          'domains': {'': {'': server.host()},
>                                      'alt':{ '': '127.0.0.1'}},
>-                         'ports': {'http': [str(server.http_port())],
>-                                   'https': [str(server.https_port())]},
>+                         'ports': {'http': [server.http_port()],
>+                                   'https': [server.https_port()]},
>                          'doc_root': server.document_root()}
>         self.runner = TestRunner()
>         WdspecExecutor.__init__(self, self.runner.logger, driver.browser_name(), server_config, driver.binary_path(), None, capabilities=driver.capabilities())
>@@ -147,13 +147,13 @@ class WebDriverW3CExecutor(WdspecExecutor):
>         self._result_queue = Queue()
> 
>     def setup(self):
>-        self.protocol.setup(self.runner)
>+        super(WebDriverW3CExecutor, self).setup(self.runner)
>         args = (self._test_queue,
>                 self._result_queue,
>                 self.protocol.session_config['host'],
>                 str(self.protocol.session_config['port']),
>                 json.dumps(self.protocol.session_config['capabilities']),
>-                json.dumps(self.server_config),
>+                self.server_config,
>                 self._timeout,
>                 self._expectations)
>         self._process = Process(target=WebDriverW3CExecutor._runner, args=args)
>@@ -174,13 +174,18 @@ class WebDriverW3CExecutor(WdspecExecutor):
>             if test == 'TEARDOWN':
>                 break
> 
>-            env = {'WD_HOST': host,
>-                   'WD_PORT': port,
>-                   'WD_CAPABILITIES': capabilities,
>-                   'WD_SERVER_CONFIG': server_config}
>-            env.update(WebKitDriverServer.test_env)
>-            args = ['--strict', '-p', 'no:mozlog']
>-            result_queue.put(pytest_runner.run(test, args, timeout, env, expectations))
>+            with pytest_runner.TemporaryDirectory() as cache_directory:
>+                server_config_path = os.path.join(cache_directory, 'wd_server_config.json')
>+                with open(server_config_path, 'w') as f:
>+                    json.dump(server_config, f)
>+
>+                env = {'WD_HOST': host,
>+                       'WD_PORT': port,
>+                       'WD_CAPABILITIES': capabilities,
>+                       'WD_SERVER_CONFIG_FILE': server_config_path}
>+                env.update(WebKitDriverServer.test_env)
>+                args = ['--strict', '-p', 'no:mozlog']
>+                result_queue.put(pytest_runner.run(test, args, timeout, env, expectations))
> 
>     def run(self, test):
>         self._test_queue.put(test)
>diff --git a/WebDriverTests/ChangeLog b/WebDriverTests/ChangeLog
>index 902b92bfef9b..6d45808f50ef 100644
>--- a/WebDriverTests/ChangeLog
>+++ b/WebDriverTests/ChangeLog
>@@ -1,3 +1,17 @@
>+2021-09-22  Carlos Garcia Campos  <cgarcia@igalia.com>
>+
>+        [WebDriver] Update w3c and selenium tests
>+        https://bugs.webkit.org/show_bug.cgi?id=230551
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        * imported/selenium/common/src/web/javascriptPage.html:
>+        * imported/selenium/importer.json:
>+        * imported/selenium/py/:
>+        * imported/w3c/importer.json:
>+        * imported/w3c/tools/:
>+        * imported/w3c/webdriver/:
>+
> 2021-08-22  Lauro Moura  <lmoura@igalia.com>
> 
>         [WPE][WebDriver] Basic fullscreen support for the headless backend
>diff --git a/WebDriverTests/TestExpectations.json b/WebDriverTests/TestExpectations.json
>index 45667f972f03..a2e670485c4e 100644
>--- a/WebDriverTests/TestExpectations.json
>+++ b/WebDriverTests/TestExpectations.json
>@@ -291,6 +291,30 @@
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+            },
>+            "test_cookie_unsupported_scheme[about]": {
>+                "expected": {"all": {"status": ["FAIL"], "bug": "webkit.org/b/230616"}}
>+            },
>+            "test_cookie_unsupported_scheme[blob]": {
>+                "expected": {"all": {"status": ["FAIL"], "bug": "webkit.org/b/230616"}}
>+            },
>+            "test_cookie_unsupported_scheme[data]": {
>+                "expected": {"all": {"status": ["FAIL"], "bug": "webkit.org/b/230616"}}
>+            },
>+            "test_cookie_unsupported_scheme[file]": {
>+                "expected": {"all": {"status": ["FAIL"], "bug": "webkit.org/b/230616"}}
>+            },
>+            "test_cookie_unsupported_scheme[ftp]": {
>+                "expected": {"all": {"status": ["FAIL"], "bug": "webkit.org/b/230616"}}
>+            },
>+            "test_cookie_unsupported_scheme[javascript]": {
>+                "expected": {"all": {"status": ["FAIL"], "bug": "webkit.org/b/230616"}}
>+            },
>+            "test_cookie_unsupported_scheme[websocket]": {
>+                "expected": {"all": {"status": ["FAIL"], "bug": "webkit.org/b/230616"}}
>+            },
>+            "test_cookie_unsupported_scheme[secure websocket]": {
>+                "expected": {"all": {"status": ["FAIL"], "bug": "webkit.org/b/230616"}}
>             }
>         }
>     },
>@@ -744,7 +768,10 @@
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/180645"}}
>             },
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -763,7 +790,10 @@
>     "imported/w3c/webdriver/tests/element_click/click.py": {
>         "subtests": {
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -935,7 +965,10 @@
>     "imported/w3c/webdriver/tests/element_send_keys/send_keys.py": {
>         "subtests": {
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -1152,7 +1185,10 @@
>     "imported/w3c/webdriver/tests/get_element_attribute/get.py": {
>         "subtests": {
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -1163,7 +1199,10 @@
>     "imported/w3c/webdriver/tests/get_element_css_value/get.py": {
>         "subtests": {
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -1174,7 +1213,10 @@
>     "imported/w3c/webdriver/tests/get_element_property/get.py": {
>         "subtests": {
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -1196,7 +1238,10 @@
>     "imported/w3c/webdriver/tests/get_element_tag_name/get.py": {
>         "subtests": {
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -1218,7 +1263,10 @@
>     "imported/w3c/webdriver/tests/get_element_text/get.py": {
>         "subtests": {
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -1368,7 +1416,10 @@
>                 "expected": {"all": {"status": ["FAIL"], "bug": "webkit.org/b/205923"}}
>             },
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -1379,7 +1430,10 @@
>     "imported/w3c/webdriver/tests/is_element_selected/selected.py": {
>         "subtests": {
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             },
>             "test_no_browsing_context": {
>                 "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/212950"}}
>@@ -1442,7 +1496,10 @@
>     "imported/w3c/webdriver/tests/switch_to_window/switch.py": {
>         "subtests": {
>             "test_no_top_browsing_context": {
>-                "expected": {"wpe": {"status": ["FAIL"], "bug": "webkit.org/b/205994"}}
>+                "expected": {
>+                    "wpe": {"status": ["FAIL"], "bug": "webkit.org/b/205994"},
>+                    "gtk": {"status": ["FAIL"], "bug": "webkit.org/b/230612"}
>+                }
>             }
>         }
>     },
>@@ -1495,5 +1552,29 @@
>     },
>     "imported/w3c/webdriver/tests/minimize_window/minimize.py" : {
>         "expected": { "wpe": { "status": ["SKIP"] } }
>+    },
>+    "imported/w3c/webdriver/tests/find_element_from_shadow_root/find.py": {
>+        "expected": { "all": { "status": ["SKIP"], "bug": "webkit.org/b/230614"}}
>+    },
>+    "imported/w3c/webdriver/tests/find_element_from_shadow_root/user_prompts.py": {
>+        "expected": { "all": { "status": ["SKIP"], "bug": "webkit.org/b/230614"}}
>+    },
>+    "imported/w3c/webdriver/tests/find_elements_from_shadow_root/find.py": {
>+        "expected": { "all": { "status": ["SKIP"], "bug": "webkit.org/b/230614"}}
>+    },
>+    "imported/w3c/webdriver/tests/find_elements_from_shadow_root/user_prompts.py": {
>+        "expected": { "all": { "status": ["SKIP"], "bug": "webkit.org/b/230614"}}
>+    },
>+    "imported/w3c/webdriver/tests/get_element_shadow_root/get.py": {
>+        "expected": { "all": { "status": ["SKIP"], "bug": "webkit.org/b/230614"}}
>+    },
>+    "imported/w3c/webdriver/tests/get_element_shadow_root/user_prompts.py": {
>+        "expected": { "all": { "status": ["SKIP"], "bug": "webkit.org/b/230614"}}
>+    },
>+    "imported/w3c/webdriver/tests/bidi/new_session/connect.py": {
>+        "expected": { "all": { "status": ["SKIP"], "bug": "webkit.org/b/230615"}}
>+    },
>+    "imported/w3c/webdriver/tests/new_session/websocket_url.py": {
>+        "expected": { "all": { "status": ["SKIP"], "bug": "webkit.org/b/230615"}}
>     }
> }
>diff --git a/WebDriverTests/imported/selenium/common/src/web/javascriptPage.html b/WebDriverTests/imported/selenium/common/src/web/javascriptPage.html
>index fcac252e899a..1690ad07dd79 100644
>--- a/WebDriverTests/imported/selenium/common/src/web/javascriptPage.html
>+++ b/WebDriverTests/imported/selenium/common/src/web/javascriptPage.html
>@@ -86,7 +86,7 @@
>   </div>
> 
> </div>
>-                                                                                         
>+
> <div id="formageddon">
>     <form action="#">
>         Key Up: <input type="text" id="keyUp" onkeyup="javascript:updateContent(this)"/><br/>
>@@ -151,15 +151,15 @@
>            />
> 
>     <input id="changeable" name="changeable" onfocus="appendMessage('focus')" onchange="appendMessage('change')" onblur="appendMessage('blur')"/>
>-           
>-    <button type="button" id="plainButton" 
>+
>+    <button type="button" id="plainButton"
>     		onfocus="appendMessage('focus')"
>            	onkeydown="appendMessage('keydown')"
>            	onkeypress="appendMessage('keypress')"
>            	onkeyup="appendMessage('keyup')"
>            	onblur="appendMessage('blur')"
>            	onclick="appendMessage('click')"
>-           	onmousedown="appendMessage('mousedown ')" 
>+           	onmousedown="appendMessage('mousedown ')"
>            	onmouseup="appendMessage('mouseup ')"
>             onmouseover="register('mouseover ')"
>             onmousemove="register('mousemove ')"
>@@ -173,7 +173,7 @@
>     <button type="button" onclick="var element = document.getElementById('switchFocus'); var clickEvent = document.createEvent('MouseEvents'); clickEvent.initMouseEvent('click', true, true, null, 0, 0, 0, 0, 0,false, false, false, false, 0, element);element.dispatchEvent(clickEvent);">Do magic</button><br/>
>     <label id="labelForCheckbox" for="labeledCheckbox" onclick="appendMessage('labelclick')">Toggle checkbox</label><input type="checkbox" id="labeledCheckbox" onclick="appendMessage('chboxclick')"/>
>   </form>
>-  
>+
>   <form action="javascriptPage.html" id="submitListeningForm" onsubmit="appendMessage('form-onsubmit '); return false;">
>     <p>
>       <input id="submitListeningForm-text" type="text" onsubmit="appendMessage('text-onsubmit ')" onclick="appendMessage('text-onclick ');" />
>@@ -198,7 +198,7 @@
>         <a href="#" id="hiddenlink">ok</a>
>       </div>
>     </div>
>-    
>+
>     <div style="visibility: hidden;">
>       <span>
>         <input id="unclickable" />
>@@ -265,7 +265,7 @@
> 
> <a id="new_window" onmouseup="window.open('closeable_window.html', 'close_me')" href="#">Click me to open a new window</a>
> 
>-<a id="throwing-mouseover" onmouseover="throw new Error()" href="#throwing-mouseover">Mouse over me will throw a JS error</a>
>+<a id="throwing-mouseover" onmouseover="throw new Error('I like cheese')" href="#throwing-mouseover">Mouse over me will throw a JS error</a>
> 
> <div id="parent">
>     <span id="movable" onmouseover="var p = document.getElementById('movable'); displayMessage('parent matches? ' + (p != event.relatedTarget));">
>diff --git a/WebDriverTests/imported/selenium/importer.json b/WebDriverTests/imported/selenium/importer.json
>index d985c8edac75..5ba0c3a5d303 100644
>--- a/WebDriverTests/imported/selenium/importer.json
>+++ b/WebDriverTests/imported/selenium/importer.json
>@@ -1,6 +1,6 @@
> {
>     "repository": "https://github.com/SeleniumHQ/selenium.git",
>-    "revision": "d4f9fe213dd6e5b10b89be360be635747ed3e138",
>+    "revision": "e3fcf791239c0e9ba5c04686025f578b561ecd6f",
>     "paths_to_import": [
>         "common",
>         "py/conftest.py",
>diff --git a/WebDriverTests/imported/selenium/py/conftest.py b/WebDriverTests/imported/selenium/py/conftest.py
>index 6d64f3ffe7c0..b2358b7f65e9 100644
>--- a/WebDriverTests/imported/selenium/py/conftest.py
>+++ b/WebDriverTests/imported/selenium/py/conftest.py
>@@ -16,31 +16,25 @@
> # under the License.
> 
> import os
>+import platform
> import socket
> import subprocess
>-import sys
> import time
> 
> import pytest
>-from _pytest.skipping import MarkEvaluator
> 
> from selenium import webdriver
> from selenium.webdriver import DesiredCapabilities
> from test.selenium.webdriver.common.webserver import SimpleWebServer
> from test.selenium.webdriver.common.network import get_lan_ip
> 
>-if sys.version_info[0] == 3:
>-    from urllib.request import urlopen
>-else:
>-    from urllib import urlopen
>+from urllib.request import urlopen
> 
> drivers = (
>-    'BlackBerry',
>     'Chrome',
>     'Edge',
>     'Firefox',
>     'Ie',
>-    'Marionette',
>     'Remote',
>     'Safari',
>     'WebKitGTK',
>@@ -82,10 +76,28 @@ def driver(request):
>     except AttributeError:
>         raise Exception('This test requires a --driver to be specified.')
> 
>+    # skip tests if not available on the platform
>+    _platform = platform.system()
>+    if driver_class == "Safari" and _platform != "Darwin":
>+        pytest.skip("Safari tests can only run on an Apple OS")
>+    if (driver_class == "Ie" or driver_class == "Edge") and _platform != "Windows":
>+        pytest.skip("IE and EdgeHTML Tests can only run on Windows")
>+    if "WebKit" in driver_class and _platform != "Linux":
>+        pytest.skip("Webkit tests can only run on Linux")
>+
>     # conditionally mark tests as expected to fail based on driver
>-    request.node._evalxfail = request.node._evalxfail or MarkEvaluator(
>-        request.node, 'xfail_{0}'.format(driver_class.lower()))
>-    if request.node._evalxfail.istrue():
>+    marker = request.node.get_closest_marker('xfail_{0}'.format(driver_class.lower()))
>+
>+    if marker is not None:
>+        if "run" in marker.kwargs:
>+            if marker.kwargs["run"] is False:
>+                pytest.skip()
>+                yield
>+                return
>+        if "raises" in marker.kwargs:
>+            marker.kwargs.pop("raises")
>+        pytest.xfail(**marker.kwargs)
>+
>         def fin():
>             global driver_instance
>             if driver_instance is not None:
>@@ -93,25 +105,12 @@ def driver(request):
>             driver_instance = None
>         request.addfinalizer(fin)
> 
>-    # skip driver instantiation if xfail(run=False)
>-    if not request.config.getoption('runxfail'):
>-        if request.node._evalxfail.istrue():
>-            if request.node._evalxfail.get('run') is False:
>-                yield
>-                return
>-
>     driver_path = request.config.option.executable
>     options = None
> 
>     global driver_instance
>     if driver_instance is None:
>-        if driver_class == 'BlackBerry':
>-            kwargs.update({'device_password': 'password'})
>         if driver_class == 'Firefox':
>-            kwargs.update({'capabilities': {'marionette': False}})
>-            options = get_options(driver_class, request.config)
>-        if driver_class == 'Marionette':
>-            driver_class = 'Firefox'
>             options = get_options(driver_class, request.config)
>         if driver_class == 'Remote':
>             capabilities = DesiredCapabilities.FIREFOX.copy()
>@@ -129,7 +128,8 @@ def driver(request):
>             kwargs['options'] = options
>         driver_instance = getattr(webdriver, driver_class)(**kwargs)
>     yield driver_instance
>-    if MarkEvaluator(request.node, 'no_driver_after_test').istrue():
>+
>+    if request.node.get_closest_marker("no_driver_after_test"):
>         driver_instance = None
> 
> 
>diff --git a/WebDriverTests/imported/selenium/py/selenium/__init__.py b/WebDriverTests/imported/selenium/py/selenium/__init__.py
>index 4a049b859132..323caaeb790c 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/__init__.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/__init__.py
>@@ -16,4 +16,4 @@
> # under the License.
> 
> 
>-__version__ = "4.0.0a6"
>+__version__ = "4.0.0a7"
>diff --git a/WebDriverTests/imported/selenium/py/selenium/common/exceptions.py b/WebDriverTests/imported/selenium/py/selenium/common/exceptions.py
>index 4cb11c89d58e..e827b07e1e3a 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/common/exceptions.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/common/exceptions.py
>@@ -158,7 +158,7 @@ class ElementNotVisibleException(InvalidElementStateException):
> class ElementNotInteractableException(InvalidElementStateException):
>     """
>     Thrown when an element is present in the DOM but interactions
>-    with that element will hit another element do to paint order
>+    with that element will hit another element due to paint order
>     """
>     pass
> 
>@@ -273,7 +273,7 @@ class ScreenshotException(WebDriverException):
> class ElementClickInterceptedException(WebDriverException):
>     """
>     The Element Click command could not be completed because the element receiving the events
>-    is obscuring the element that was requested clicked.
>+    is obscuring the element that was requested to be clicked.
>     """
>     pass
> 
>@@ -288,7 +288,7 @@ class InsecureCertificateException(WebDriverException):
> 
> class InvalidCoordinatesException(WebDriverException):
>     """
>-    The coordinates provided to an interactions operation are invalid.
>+    The coordinates provided to an interaction's operation are invalid.
>     """
>     pass
> 
>diff --git a/WebDriverTests/imported/selenium/py/selenium/webdriver/__init__.py b/WebDriverTests/imported/selenium/py/selenium/webdriver/__init__.py
>index 9b93dcc2847c..e757636ac75b 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/webdriver/__init__.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/webdriver/__init__.py
>@@ -16,14 +16,14 @@
> # under the License.
> 
> from .safari.webdriver import WebDriver as Safari  # noqa
>-from .webkitgtk.webdriver import WebDriver as WebKitGTK # noqa
>-from .webkitgtk.options import Options as WebKitGTKOptions # noqa
>-from .wpewebkit.webdriver import WebDriver as WPEWebKit # noqa
>-from .wpewebkit.options import Options as WPEWebKitOptions # noqa
>+from .webkitgtk.webdriver import WebDriver as WebKitGTK  # noqa
>+from .webkitgtk.options import Options as WebKitGTKOptions  # noqa
>+from .wpewebkit.webdriver import WebDriver as WPEWebKit  # noqa
>+from .wpewebkit.options import Options as WPEWebKitOptions  # noqa
> from .remote.webdriver import WebDriver as Remote  # noqa
> from .common.desired_capabilities import DesiredCapabilities  # noqa
> from .common.action_chains import ActionChains  # noqa
> from .common.touch_actions import TouchActions  # noqa
> from .common.proxy import Proxy  # noqa
> 
>-__version__ = '4.0.0a6'
>+__version__ = '4.0.0a7'
>diff --git a/WebDriverTests/imported/selenium/py/selenium/webdriver/common/options.py b/WebDriverTests/imported/selenium/py/selenium/webdriver/common/options.py
>index bff251727b3e..9203481289d2 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/webdriver/common/options.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/webdriver/common/options.py
>@@ -49,12 +49,12 @@ class BaseOptions(object):
>         """Return minimal capabilities necessary as a dictionary."""
> 
> 
>-
> class ArgOptions(BaseOptions):
> 
>     def __init__(self):
>         super(ArgOptions, self).__init__()
>         self._arguments = []
>+        self._ignore_local_proxy = False
> 
>     @property
>     def arguments(self):
>@@ -75,6 +75,12 @@ class ArgOptions(BaseOptions):
>         else:
>             raise ValueError('argument can not be null')
> 
>+    def ignore_local_proxy_environment_variables(self):
>+        """
>+            By calling this you will ignore HTTP_PROXY and HTTPS_PROXY from being picked up and used.
>+        """
>+        self._ignore_local_proxy = True
>+
>     def to_capabilities(self):
>         return self._caps
> 
>diff --git a/WebDriverTests/imported/selenium/py/selenium/webdriver/common/service.py b/WebDriverTests/imported/selenium/py/selenium/webdriver/common/service.py
>index d20a902fac7e..8c32e0dbecc1 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/webdriver/common/service.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/webdriver/common/service.py
>@@ -46,6 +46,8 @@ class Service(object):
> 
>         self.start_error_message = start_error_message
>         self.log_file = log_file
>+        # Default value for every python subprocess: subprocess.Popen(..., creationflags=0)
>+        self.creationflags = 0
>         self.env = env or os.environ
> 
>     @property
>@@ -73,7 +75,8 @@ class Service(object):
>                                             close_fds=platform.system() != 'Windows',
>                                             stdout=self.log_file,
>                                             stderr=self.log_file,
>-                                            stdin=PIPE)
>+                                            stdin=PIPE,
>+                                            creationflags=self.creationflags)
>         except TypeError:
>             raise
>         except OSError as err:
>@@ -98,9 +101,10 @@ class Service(object):
>             self.assert_process_still_running()
>             if self.is_connectable():
>                 break
>+
>             count += 1
>-            time.sleep(1)
>-            if count == 30:
>+            time.sleep(0.5)
>+            if count == 60:
>                 raise WebDriverException("Can not connect to the Service %s" % self.path)
> 
>     def assert_process_still_running(self):
>diff --git a/WebDriverTests/imported/selenium/py/selenium/webdriver/common/utils.py b/WebDriverTests/imported/selenium/py/selenium/webdriver/common/utils.py
>index 957f2fd26699..1f60e44573a2 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/webdriver/common/utils.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/webdriver/common/utils.py
>@@ -36,7 +36,7 @@ def free_port():
>     Determines a free port using sockets.
>     """
>     free_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>-    free_socket.bind(('0.0.0.0', 0))
>+    free_socket.bind(('127.0.0.1', 0))
>     free_socket.listen(5)
>     port = free_socket.getsockname()[1]
>     free_socket.close()
>diff --git a/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/remote_connection.py b/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/remote_connection.py
>index 6f1c1b471207..2448c1b06b4c 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/remote_connection.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/remote_connection.py
>@@ -141,7 +141,7 @@ class RemoteConnection(object):
>         return urllib3.PoolManager(**pool_manager_init_args) if self._proxy_url is None else \
>             urllib3.ProxyManager(self._proxy_url, **pool_manager_init_args)
> 
>-    def __init__(self, remote_server_addr, keep_alive=False, resolve_ip=None):
>+    def __init__(self, remote_server_addr, keep_alive=False, resolve_ip=None, ignore_proxy=False):
>         if resolve_ip is not None:
>             import warnings
>             warnings.warn(
>@@ -149,7 +149,7 @@ class RemoteConnection(object):
>                 DeprecationWarning)
>         self.keep_alive = keep_alive
>         self._url = remote_server_addr
>-        self._proxy_url = self._get_proxy_url()
>+        self._proxy_url = self._get_proxy_url() if not ignore_proxy else None
>         if keep_alive:
>             self._conn = self._get_connection_manager()
> 
>@@ -197,7 +197,7 @@ class RemoteConnection(object):
>                 ('POST', '/session/$sessionId/element/$id/value'),
>             Command.SEND_KEYS_TO_ACTIVE_ELEMENT:
>                 ('POST', '/session/$sessionId/keys'),
>-            Command.UPLOAD_FILE: ('POST', "/session/$sessionId/file"),
>+            Command.UPLOAD_FILE: ('POST', "/session/$sessionId/se/file"),
>             Command.GET_ELEMENT_VALUE:
>                 ('GET', '/session/$sessionId/element/$id/value'),
>             Command.GET_ELEMENT_TAG_NAME:
>diff --git a/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/webdriver.py b/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/webdriver.py
>index 62282d52695b..c483103d3a50 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/webdriver.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/webdriver.py
>@@ -20,19 +20,23 @@
> from abc import ABCMeta
> import base64
> import copy
>-from contextlib import contextmanager
>+from contextlib import (contextmanager, asynccontextmanager)
>+import importlib
> import pkgutil
> import warnings
>+import sys
> 
> from .command import Command
> from .errorhandler import ErrorHandler
> from .file_detector import FileDetector, LocalFileDetector
> from .mobile import Mobile
> from .remote_connection import RemoteConnection
>+from .script_key import ScriptKey
> from .switch_to import SwitchTo
> from .webelement import WebElement
> 
> from selenium.common.exceptions import (InvalidArgumentException,
>+                                        JavascriptException,
>                                         WebDriverException,
>                                         NoSuchCookieException,
>                                         UnknownMethodException)
>@@ -48,6 +52,14 @@ try:
> except NameError:
>     pass
> 
>+cdp = None
>+
>+
>+def import_cdp():
>+    global cdp
>+    if cdp is None:
>+        cdp = importlib.import_module("selenium.webdriver.common.bidi.cdp")
>+
> 
> _W3C_CAPABILITY_NAMES = frozenset([
>     'acceptInsecureCerts',
>@@ -68,6 +80,8 @@ _OSS_W3C_CONVERSION = {
>     'platform': 'platformName'
> }
> 
>+devtools = None
>+
> 
> def _make_w3c_caps(caps):
>     """Makes a W3C alwaysMatch capabilities object.
>@@ -102,7 +116,7 @@ def _make_w3c_caps(caps):
>     return {"firstMatch": [{}], "alwaysMatch": always_match}
> 
> 
>-def get_remote_connection(capabilities, command_executor, keep_alive):
>+def get_remote_connection(capabilities, command_executor, keep_alive, ignore_local_proxy=False):
>     from selenium.webdriver.safari.remote_connection import SafariRemoteConnection
> 
>     candidates = [RemoteConnection] + [SafariRemoteConnection]
>@@ -111,7 +125,7 @@ def get_remote_connection(capabilities, command_executor, keep_alive):
>         RemoteConnection
>     )
> 
>-    return handler(command_executor, keep_alive=keep_alive)
>+    return handler(command_executor, keep_alive=keep_alive, ignore_proxy=ignore_local_proxy)
> 
> 
> @add_metaclass(ABCMeta)
>@@ -163,8 +177,10 @@ class WebDriver(BaseWebDriver):
>          - options - instance of a driver options.Options class
>         """
>         capabilities = {}
>+        _ignore_local_proxy = False
>         if options is not None:
>             capabilities = options.to_capabilities()
>+            _ignore_local_proxy = options._ignore_local_proxy
>         if desired_capabilities is not None:
>             if not isinstance(desired_capabilities, dict):
>                 raise WebDriverException("Desired Capabilities must be a dictionary")
>@@ -172,10 +188,13 @@ class WebDriver(BaseWebDriver):
>                 capabilities.update(desired_capabilities)
>         self.command_executor = command_executor
>         if isinstance(self.command_executor, (str, bytes)):
>-            self.command_executor = get_remote_connection(capabilities, command_executor=command_executor, keep_alive=keep_alive)
>+            self.command_executor = get_remote_connection(capabilities, command_executor=command_executor,
>+                                                          keep_alive=keep_alive,
>+                                                          ignore_local_proxy=_ignore_local_proxy)
>         self._is_remote = True
>         self.session_id = None
>-        self.capabilities = {}
>+        self.caps = {}
>+        self.pinned_scripts = {}
>         self.error_handler = ErrorHandler()
>         self.start_client()
>         self.start_session(capabilities, browser_profile)
>@@ -235,8 +254,8 @@ class WebDriver(BaseWebDriver):
> 
>                 name = driver.name
>         """
>-        if 'browserName' in self.capabilities:
>-            return self.capabilities['browserName']
>+        if 'browserName' in self.caps:
>+            return self.caps['browserName']
>         else:
>             raise KeyError('browserName not specified in session capabilities')
> 
>@@ -279,12 +298,12 @@ class WebDriver(BaseWebDriver):
>         if 'sessionId' not in response:
>             response = response['value']
>         self.session_id = response['sessionId']
>-        self.capabilities = response.get('value')
>+        self.caps = response.get('value')
> 
>         # if capabilities is none we are probably speaking to
>         # a W3C endpoint
>-        if self.capabilities is None:
>-            self.capabilities = response.get('capabilities')
>+        if self.caps is None:
>+            self.caps = response.get('capabilities')
> 
>         # Double check to see if we have a W3C Compliant browser
>         self.w3c = response.get('status') is None
>@@ -689,6 +708,26 @@ class WebDriver(BaseWebDriver):
>         warnings.warn("find_elements_by_* commands are deprecated. Please use find_elements() instead")
>         return self.find_elements(by=By.CSS_SELECTOR, value=css_selector)
> 
>+    def pin_script(self, script):
>+        """
>+
>+        """
>+        script_key = ScriptKey()
>+        self.pinned_scripts[script_key.id] = script
>+        return script_key
>+
>+    def unpin(self, script_key):
>+        """
>+
>+        """
>+        self.pinned_scripts.pop(script_key.id)
>+
>+    def get_pinned_scripts(self):
>+        """
>+
>+        """
>+        return list(self.pinned_scripts.keys())
>+
>     def execute_script(self, script, *args):
>         """
>         Synchronously Executes JavaScript in the current window/frame.
>@@ -702,6 +741,12 @@ class WebDriver(BaseWebDriver):
> 
>                 driver.execute_script('return document.title;')
>         """
>+        if isinstance(script, ScriptKey):
>+            try:
>+                script = self.pinned_scripts[script.id]
>+            except KeyError:
>+                raise JavascriptException("Pinned script could not be found")
>+
>         converted_args = list(args)
>         command = None
>         if self.w3c:
>@@ -1067,8 +1112,7 @@ class WebDriver(BaseWebDriver):
> 
>     def find_element(self, by=By.ID, value=None):
>         """
>-        Find an element given a By strategy and locator. Prefer the find_element_by_* methods when
>-        possible.
>+        Find an element given a By strategy and locator.
> 
>         :Usage:
>             ::
>@@ -1095,8 +1139,7 @@ class WebDriver(BaseWebDriver):
> 
>     def find_elements(self, by=By.ID, value=None):
>         """
>-        Find elements given a By strategy and locator. Prefer the find_elements_by_* methods when
>-        possible.
>+        Find elements given a By strategy and locator.
> 
>         :Usage:
>             ::
>@@ -1108,7 +1151,7 @@ class WebDriver(BaseWebDriver):
>         if isinstance(by, RelativeBy):
>             _pkg = '.'.join(__name__.split('.')[:-1])
>             raw_function = pkgutil.get_data(_pkg, 'findElements.js').decode('utf8')
>-            find_element_js = "return (%s).apply(null, arguments);" % raw_function
>+            find_element_js = "return ({}).apply(null, arguments);".format(raw_function)
>             return self.execute_script(find_element_js, by.to_dict())
> 
>         if self.w3c:
>@@ -1135,7 +1178,16 @@ class WebDriver(BaseWebDriver):
>         """
>         returns the drivers current desired capabilities being used
>         """
>-        return self.capabilities
>+        warnings.warn("desired_capabilities is deprecated. Please call capabilities.",
>+                      DeprecationWarning, stacklevel=2)
>+        return self.caps
>+
>+    @property
>+    def capabilities(self):
>+        """
>+        returns the drivers current capabilities being used.
>+        """
>+        return self.caps
> 
>     def get_screenshot_as_file(self, filename):
>         """
>@@ -1417,3 +1469,110 @@ class WebDriver(BaseWebDriver):
>                 driver.get_log('server')
>         """
>         return self.execute(Command.GET_LOG, {'type': log_type})['value']
>+
>+    @asynccontextmanager
>+    async def add_js_error_listener(self):
>+        """
>+        Listens for JS errors and when the contextmanager exits check if there were JS Errors
>+
>+        :Usage:
>+             ::
>+
>+                async with driver.add_js_error_listener() as error:
>+                    driver.find_element(By.ID, "throwing-mouseover").click()
>+                assert error is not None
>+                assert error.exception_details.stack_trace.call_frames[0].function_name == "onmouseover"
>+        """
>+        assert sys.version_info >= (3, 7)
>+        global cdp
>+        async with self._get_bidi_connection():
>+            global devtools
>+            session = cdp.get_session_context('page.enable')
>+            await session.execute(devtools.page.enable())
>+            session = cdp.get_session_context('runtime.enable')
>+            await session.execute(devtools.runtime.enable())
>+            js_exception = devtools.runtime.ExceptionThrown(None, None)
>+            async with session.wait_for(devtools.runtime.ExceptionThrown) as exception:
>+                yield js_exception
>+            js_exception.timestamp = exception.value.timestamp
>+            js_exception.exception_details = exception.value.exception_details
>+
>+    @asynccontextmanager
>+    async def add_listener(self, event_type):
>+        '''
>+        Listens for certain events that are passed in.
>+
>+        :Args:
>+         - event_type: The type of event that we want to look at.
>+
>+         :Usage:
>+             ::
>+
>+                async with driver.add_listener(Console.log) as messages:
>+                    driver.execute_script("console.log('I like cheese')")
>+                assert messages["message"] == "I love cheese"
>+
>+        '''
>+        assert sys.version_info >= (3, 7)
>+        global cdp
>+        from selenium.webdriver.common.bidi.console import Console
>+
>+        async with self._get_bidi_connection():
>+            global devtools
>+            session = cdp.get_session_context('page.enable')
>+            await session.execute(devtools.page.enable())
>+            session = cdp.get_session_context('console.enable')
>+            await session.execute(devtools.console.enable())
>+            console = {
>+                "message": None,
>+                "level": None
>+            }
>+            async with session.wait_for(devtools.console.MessageAdded) as messages:
>+                yield console
>+            if event_type == Console.ERROR:
>+                if messages.value.message.level == "error":
>+                    console["message"] = messages.value.message.text
>+                    console["level"] = messages.value.message.level
>+            elif event_type == Console.ALL:
>+                console["message"] = messages.value.message.text
>+                console["level"] = messages.value.message.level
>+
>+    @asynccontextmanager
>+    async def _get_bidi_connection(self):
>+        global cdp
>+        import_cdp()
>+        ws_url = None
>+        if self.caps.get("se:options"):
>+            ws_url = self.caps.get("se:options").get("cdp")
>+        else:
>+            version, ws_url = self._get_cdp_details()
>+
>+        if ws_url is None:
>+            raise WebDriverException("Unable to find url to connect to from capabilities")
>+
>+        cdp.import_devtools(version)
>+
>+        global devtools
>+        devtools = importlib.import_module("selenium.webdriver.common.devtools.v{}".format(version))
>+        async with cdp.open_cdp(ws_url) as conn:
>+            targets = await conn.execute(devtools.target.get_targets())
>+            target_id = targets[0].target_id
>+            async with conn.open_session(target_id) as session:
>+                yield session
>+
>+    def _get_cdp_details(self):
>+        import json
>+        import urllib3
>+
>+        http = urllib3.PoolManager()
>+        debugger_address = self.caps.get("{0}:chromeOptions".format(self.vendor_prefix)).get("debuggerAddress")
>+        res = http.request('GET', "http://{0}/json/version".format(debugger_address))
>+        data = json.loads(res.data)
>+
>+        browser_version = data.get("Browser")
>+        websocket_url = data.get("webSocketDebuggerUrl")
>+
>+        import re
>+        version = re.search(r".*/(\d+)\.", browser_version).group(1)
>+
>+        return version, websocket_url
>diff --git a/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/webelement.py b/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/webelement.py
>index 6f3ebbcc3b54..093e42a5ba13 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/webelement.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/webdriver/remote/webelement.py
>@@ -534,9 +534,14 @@ class WebElement(BaseWebElement):
>         # transfer file to another machine only if remote driver is used
>         # the same behaviour as for java binding
>         if self.parent._is_remote:
>-            local_file = self.parent.file_detector.is_local_file(*value)
>-            if local_file is not None:
>-                value = self._upload(local_file)
>+            local_files = list(map(lambda keys_to_send:
>+                                   self.parent.file_detector.is_local_file(keys_to_send),
>+                                   ''.join(value).split('\n')))
>+            if None not in local_files:
>+                remote_files = []
>+                for file in local_files:
>+                    remote_files.append(self._upload(file))
>+                value = '\n'.join(remote_files)
> 
>         self._execute(Command.SEND_KEYS_TO_ELEMENT,
>                       {'text': "".join(keys_to_typing(value)),
>@@ -704,8 +709,7 @@ class WebElement(BaseWebElement):
> 
>     def find_element(self, by=By.ID, value=None):
>         """
>-        Find an element given a By strategy and locator. Prefer the find_element_by_* methods when
>-        possible.
>+        Find an element given a By strategy and locator.
> 
>         :Usage:
>             ::
>@@ -732,8 +736,7 @@ class WebElement(BaseWebElement):
> 
>     def find_elements(self, by=By.ID, value=None):
>         """
>-        Find elements given a By strategy and locator. Prefer the find_elements_by_* methods when
>-        possible.
>+        Find elements given a By strategy and locator.
> 
>         :Usage:
>             ::
>diff --git a/WebDriverTests/imported/selenium/py/selenium/webdriver/safari/remote_connection.py b/WebDriverTests/imported/selenium/py/selenium/webdriver/safari/remote_connection.py
>index 22c623e610af..d692428998f5 100644
>--- a/WebDriverTests/imported/selenium/py/selenium/webdriver/safari/remote_connection.py
>+++ b/WebDriverTests/imported/selenium/py/selenium/webdriver/safari/remote_connection.py
>@@ -23,8 +23,8 @@ class SafariRemoteConnection(RemoteConnection):
> 
>     browser_name = DesiredCapabilities.SAFARI['browserName']
> 
>-    def __init__(self, remote_server_addr, keep_alive=True):
>-        RemoteConnection.__init__(self, remote_server_addr, keep_alive)
>+    def __init__(self, remote_server_addr, keep_alive=True, ignore_proxy=False):
>+        RemoteConnection.__init__(self, remote_server_addr, keep_alive, ignore_proxy=ignore_proxy)
> 
>         self._commands["GET_PERMISSIONS"] = ('GET', '/session/$sessionId/apple/permissions')
>         self._commands["SET_PERMISSIONS"] = ('POST', '/session/$sessionId/apple/permissions')
>diff --git a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/api_example_tests.py b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/api_example_tests.py
>index 397492549c2d..2e7a06b4efe8 100644
>--- a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/api_example_tests.py
>+++ b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/api_example_tests.py
>@@ -1,20 +1,3 @@
>-# Licensed to the Software Freedom Conservancy (SFC) under one
>-# or more contributor license agreements.  See the NOTICE file
>-# distributed with this work for additional information
>-# regarding copyright ownership.  The SFC licenses this file
>-# to you under the Apache License, Version 2.0 (the
>-# "License"); you may not use this file except in compliance
>-# with the License.  You may obtain a copy of the License at
>-#
>-#   http://www.apache.org/licenses/LICENSE-2.0
>-#
>-# Unless required by applicable law or agreed to in writing,
>-# software distributed under the License is distributed on an
>-# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
>-# KIND, either express or implied.  See the License for the
>-# specific language governing permissions and limitations
>-# under the License.
>-
> # Copyright 2008-2009 WebDriver committers
> # Copyright 2008-2009 Google Inc.
> #
>diff --git a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/click_scrolling_tests.py b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/click_scrolling_tests.py
>index ca0d0800a32c..4c91c227f0db 100644
>--- a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/click_scrolling_tests.py
>+++ b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/click_scrolling_tests.py
>@@ -178,14 +178,14 @@ def getScrollTop(driver):
>     return driver.execute_script("return document.body.scrollTop")
> 
> 
>-@pytest.mark.xfail_firefox(
>-    reason='https://github.com/w3c/webdriver/issues/408')
>-@pytest.mark.xfail_remote(
>-    reason='https://github.com/w3c/webdriver/issues/408')
>-@pytest.mark.xfail_safari
>-def testShouldBeAbleToClickElementInATallFrame(driver, pages):
>-    pages.load("scrolling_tests/page_with_tall_frame.html")
>-    driver.switch_to.frame(driver.find_element(By.NAME, "tall_frame"))
>-    element = driver.find_element(By.NAME, "checkbox")
>-    element.click()
>-    assert element.is_selected()
>+# @pytest.mark.xfail_firefox(
>+#     reason='https://github.com/w3c/webdriver/issues/408')
>+# @pytest.mark.xfail_remote(
>+#     reason='https://github.com/w3c/webdriver/issues/408')
>+# @pytest.mark.xfail_safari
>+# def testShouldBeAbleToClickElementInATallFrame(driver, pages):
>+#     pages.load("scrolling_tests/page_with_tall_frame.html")
>+#     driver.switch_to.frame(driver.find_element(By.NAME, "tall_frame"))
>+#     element = driver.find_element(By.NAME, "checkbox")
>+#     element.click()
>+#     assert element.is_selected()
>diff --git a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/driver_element_finding_tests.py b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/driver_element_finding_tests.py
>index d6e784280573..9b801dc30d7c 100644
>--- a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/driver_element_finding_tests.py
>+++ b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/driver_element_finding_tests.py
>@@ -335,16 +335,16 @@ def test_Finding_ALink_By_Xpath_Using_Contains_Keyword_Should_Work(driver, pages
>     assert "hello world" in element.text
> 
> 
>-@pytest.mark.xfail_chrome(raises=InvalidSelectorException)
>-@pytest.mark.xfail_chromiumedge(raises=InvalidSelectorException)
>-@pytest.mark.xfail_firefox(raises=InvalidSelectorException)
>-@pytest.mark.xfail_remote(raises=InvalidSelectorException)
>-@pytest.mark.xfail_safari(raises=NoSuchElementException)
>-@pytest.mark.xfail_webkitgtk(raises=InvalidSelectorException)
>-def test_Should_Be_Able_To_Find_Element_By_XPath_With_Namespace(driver, pages):
>-    pages.load("svgPage.html")
>-    element = driver.find_element(By.XPATH, "//svg:svg//svg:text")
>-    assert element.text == "Test Chart"
>+# @pytest.mark.xfail_chrome(raises=InvalidSelectorException)
>+# @pytest.mark.xfail_chromiumedge(raises=InvalidSelectorException)
>+# @pytest.mark.xfail_firefox(raises=InvalidSelectorException)
>+# @pytest.mark.xfail_remote(raises=InvalidSelectorException)
>+# @pytest.mark.xfail_safari(raises=NoSuchElementException)
>+# @pytest.mark.xfail_webkitgtk(raises=InvalidSelectorException)
>+# def test_Should_Be_Able_To_Find_Element_By_XPath_With_Namespace(driver, pages):
>+#     pages.load("svgPage.html")
>+#     element = driver.find_element(By.XPATH, "//svg:svg//svg:text")
>+#     assert element.text == "Test Chart"
> 
> 
> def test_Should_Be_Able_To_Find_Element_By_XPath_In_Xml_Document(driver, pages):
>diff --git a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/frame_switching_tests.py b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/frame_switching_tests.py
>index 8a759b600b98..18b346575816 100644
>--- a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/frame_switching_tests.py
>+++ b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/frame_switching_tests.py
>@@ -368,23 +368,23 @@ def testShouldBeAbleToSwitchToTheTopIfTheFrameIsDeletedFromUnderUsWithWebelement
>     WebDriverWait(driver, 3).until(EC.presence_of_element_located((By.ID, "success")))
> 
> 
>-@pytest.mark.xfail_chrome(raises=NoSuchElementException)
>-@pytest.mark.xfail_chromiumedge(raises=NoSuchElementException)
>-@pytest.mark.xfail_firefox(raises=WebDriverException,
>-                           reason='https://github.com/mozilla/geckodriver/issues/614')
>-@pytest.mark.xfail_remote(raises=WebDriverException,
>-                          reason='https://github.com/mozilla/geckodriver/issues/614')
>-@pytest.mark.xfail_webkitgtk(raises=NoSuchElementException)
>-@pytest.mark.xfail_safari
>-def testShouldNotBeAbleToDoAnythingTheFrameIsDeletedFromUnderUs(driver, pages):
>-    pages.load("frame_switching_tests/deletingFrame.html")
>-    driver.switch_to.frame(driver.find_element(By.ID, "iframe1"))
>-
>-    killIframe = driver.find_element(By.ID, "killIframe")
>-    killIframe.click()
>-
>-    with pytest.raises(NoSuchFrameException):
>-        driver.find_element(By.ID, "killIframe").click()
>+# @pytest.mark.xfail_chrome(raises=NoSuchElementException)
>+# @pytest.mark.xfail_chromiumedge(raises=NoSuchElementException)
>+# @pytest.mark.xfail_firefox(raises=WebDriverException,
>+#                            reason='https://github.com/mozilla/geckodriver/issues/614')
>+# @pytest.mark.xfail_remote(raises=WebDriverException,
>+#                           reason='https://github.com/mozilla/geckodriver/issues/614')
>+# @pytest.mark.xfail_webkitgtk(raises=NoSuchElementException)
>+# @pytest.mark.xfail_safari
>+# def testShouldNotBeAbleToDoAnythingTheFrameIsDeletedFromUnderUs(driver, pages):
>+#     pages.load("frame_switching_tests/deletingFrame.html")
>+#     driver.switch_to.frame(driver.find_element(By.ID, "iframe1"))
>+
>+#     killIframe = driver.find_element(By.ID, "killIframe")
>+#     killIframe.click()
>+
>+#     with pytest.raises(NoSuchFrameException):
>+#         driver.find_element(By.ID, "killIframe").click()
> 
> 
> def testShouldReturnWindowTitleInAFrameset(driver, pages):
>diff --git a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/page_loading_tests.py b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/page_loading_tests.py
>index 1411ee59da1b..9bc7a5b50ecd 100644
>--- a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/page_loading_tests.py
>+++ b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/page_loading_tests.py
>@@ -15,12 +15,12 @@
> # specific language governing permissions and limitations
> # under the License.
> 
>-import pytest
>-
>-from selenium.common.exceptions import WebDriverException
>-from selenium.webdriver.common.by import By
>-from selenium.webdriver.support.wait import WebDriverWait
>-from selenium.webdriver.support import expected_conditions as EC
>+# import pytest
>+#
>+# from selenium.common.exceptions import WebDriverException
>+# from selenium.webdriver.common.by import By
>+# from selenium.webdriver.support.wait import WebDriverWait
>+# from selenium.webdriver.support import expected_conditions as EC
> 
> 
> def testShouldWaitForDocumentToBeLoaded(driver, pages):
>@@ -40,25 +40,25 @@ def testShouldWaitForDocumentToBeLoaded(driver, pages):
> #    assert driver.title == "We Arrive Here"
> 
> 
>-def testShouldBeAbleToGetAFragmentOnTheCurrentPage(driver, pages):
>-    pages.load("xhtmlTest.html")
>-    location = driver.current_url
>-    driver.get(location + "#text")
>-    driver.find_element(by=By.ID, value="id1")
>+# def testShouldBeAbleToGetAFragmentOnTheCurrentPage(driver, pages):
>+#     pages.load("xhtmlTest.html")
>+#     location = driver.current_url
>+#     driver.get(location + "#text")
>+#     driver.find_element(by=By.ID, value="id1")
> 
> 
>-@pytest.mark.xfail_firefox(raises=WebDriverException)
>-@pytest.mark.xfail_remote(raises=WebDriverException)
>-def testShouldReturnWhenGettingAUrlThatDoesNotResolve(driver):
>-    #  Of course, we're up the creek if this ever does get registered
>-    driver.get("http://www.thisurldoesnotexist.comx/")
>+# @pytest.mark.xfail_firefox(raises=WebDriverException)
>+# @pytest.mark.xfail_remote(raises=WebDriverException)
>+# def testShouldReturnWhenGettingAUrlThatDoesNotResolve(driver):
>+#     #  Of course, we're up the creek if this ever does get registered
>+#     driver.get("http://www.thisurldoesnotexist.comx/")
> 
> 
>-@pytest.mark.xfail_firefox(raises=WebDriverException)
>-@pytest.mark.xfail_remote(raises=WebDriverException)
>-def testShouldReturnWhenGettingAUrlThatDoesNotConnect(driver):
>-    #  Here's hoping that there's nothing here. There shouldn't be
>-    driver.get("http://localhost:3001")
>+# @pytest.mark.xfail_firefox(raises=WebDriverException)
>+# @pytest.mark.xfail_remote(raises=WebDriverException)
>+# def testShouldReturnWhenGettingAUrlThatDoesNotConnect(driver):
>+#     #  Here's hoping that there's nothing here. There shouldn't be
>+#     driver.get("http://localhost:3001")
> 
> # def testShouldBeAbleToLoadAPageWithFramesetsAndWaitUntilAllFramesAreLoaded() {
> #     driver.get(pages.framesetPage)
>@@ -81,55 +81,55 @@ def testShouldReturnWhenGettingAUrlThatDoesNotConnect(driver):
> #     self.assertEqual(driver.title, anyOf(equalTo(originalTitle), equalTo("We Leave From Here")));
> 
> 
>-@pytest.mark.xfail_safari
>-def testShouldBeAbleToNavigateBackInTheBrowserHistory(driver, pages):
>-    pages.load("formPage.html")
>+# @pytest.mark.xfail_safari
>+# def testShouldBeAbleToNavigateBackInTheBrowserHistory(driver, pages):
>+#     pages.load("formPage.html")
> 
>-    driver.find_element(by=By.ID, value="imageButton").submit()
>-    WebDriverWait(driver, 3).until(EC.title_is("We Arrive Here"))
>+#     driver.find_element(by=By.ID, value="imageButton").submit()
>+#     WebDriverWait(driver, 3).until(EC.title_is("We Arrive Here"))
> 
>-    driver.back()
>-    assert driver.title == "We Leave From Here"
>+#     driver.back()
>+#     assert driver.title == "We Leave From Here"
> 
> 
>-@pytest.mark.xfail_safari
>-def testShouldBeAbleToNavigateBackInTheBrowserHistoryInPresenceOfIframes(driver, pages):
>-    pages.load("xhtmlTest.html")
>+# @pytest.mark.xfail_safari
>+# def testShouldBeAbleToNavigateBackInTheBrowserHistoryInPresenceOfIframes(driver, pages):
>+#     pages.load("xhtmlTest.html")
> 
>-    driver.find_element(by=By.NAME, value="sameWindow").click()
>+#     driver.find_element(by=By.NAME, value="sameWindow").click()
> 
>-    assert driver.title == "This page has iframes"
>+#     assert driver.title == "This page has iframes"
> 
>-    driver.back()
>-    assert driver.title == "XHTML Test Page"
>+#     driver.back()
>+#     assert driver.title == "XHTML Test Page"
> 
> 
>-def testShouldBeAbleToNavigateForwardsInTheBrowserHistory(driver, pages):
>-    pages.load("formPage.html")
>+# def testShouldBeAbleToNavigateForwardsInTheBrowserHistory(driver, pages):
>+#     pages.load("formPage.html")
> 
>-    driver.find_element(by=By.ID, value="imageButton").submit()
>-    WebDriverWait(driver, 3).until(EC.title_is("We Arrive Here"))
>+#     driver.find_element(by=By.ID, value="imageButton").submit()
>+#     WebDriverWait(driver, 3).until(EC.title_is("We Arrive Here"))
> 
>-    driver.back()
>-    assert driver.title == "We Leave From Here"
>+#     driver.back()
>+#     assert driver.title == "We Leave From Here"
> 
>-    driver.forward()
>-    assert driver.title == "We Arrive Here"
>+#     driver.forward()
>+#     assert driver.title == "We Arrive Here"
> 
> 
>-@pytest.mark.xfail_ie
>-@pytest.mark.xfail_firefox(run=False)
>-@pytest.mark.xfail_remote(run=False)
>-@pytest.mark.xfail_chrome(run=False)
>-@pytest.mark.xfail_chromiumedge(run=False)
>-def testShouldNotHangifDocumentOpenCallIsNeverFollowedByDocumentCloseCall(driver, pages):
>-    pages.load("document_write_in_onload.html")
>-    driver.find_element(By.XPATH, "//body")
>+# @pytest.mark.xfail_ie
>+# @pytest.mark.xfail_firefox(run=False)
>+# @pytest.mark.xfail_remote(run=False)
>+# @pytest.mark.xfail_chrome(run=False)
>+# @pytest.mark.xfail_chromiumedge(run=False)
>+# def testShouldNotHangifDocumentOpenCallIsNeverFollowedByDocumentCloseCall(driver, pages):
>+#     pages.load("document_write_in_onload.html")
>+#     driver.find_element(By.XPATH, "//body")
> 
> 
>-def testShouldBeAbleToRefreshAPage(driver, pages):
>-    pages.load("xhtmlTest.html")
>+# def testShouldBeAbleToRefreshAPage(driver, pages):
>+#     pages.load("xhtmlTest.html")
> 
>-    driver.refresh()
>+#     driver.refresh()
> 
>-    assert driver.title == "XHTML Test Page"
>+#     assert driver.title == "XHTML Test Page"
>diff --git a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/script_pinning_tests.py b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/script_pinning_tests.py
>new file mode 100644
>index 000000000000..5ef9ce3a7f5e
>--- /dev/null
>+++ b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/script_pinning_tests.py
>@@ -0,0 +1,69 @@
>+# Licensed to the Software Freedom Conservancy (SFC) under one
>+# or more contributor license agreements.  See the NOTICE file
>+# distributed with this work for additional information
>+# regarding copyright ownership.  The SFC licenses this file
>+# to you under the Apache License, Version 2.0 (the
>+# "License"); you may not use this file except in compliance
>+# with the License.  You may obtain a copy of the License at
>+#
>+#   http://www.apache.org/licenses/LICENSE-2.0
>+#
>+# Unless required by applicable law or agreed to in writing,
>+# software distributed under the License is distributed on an
>+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
>+# KIND, either express or implied.  See the License for the
>+# specific language governing permissions and limitations
>+# under the License.
>+
>+import pytest
>+
>+from selenium.common.exceptions import JavascriptException
>+
>+
>+def test_should_allow_script_pinning(driver, pages):
>+    pages.load("simpleTest.html")
>+    driver.pinned_scripts = {}
>+    script_key = driver.pin_script("return 'i like cheese';")
>+
>+    result = driver.execute_script(script_key)
>+
>+    assert result == 'i like cheese'
>+
>+
>+def test_should_allow_pinned_scripts_to_take_arguments(driver, pages):
>+    pages.load("simpleTest.html")
>+    driver.pinned_scripts = {}
>+    hello = driver.pin_script("return arguments[0]")
>+
>+    result = driver.execute_script(hello, "cheese")
>+
>+    assert result == "cheese"
>+
>+
>+def test_should_list_all_pinned_scripts(driver, pages):
>+    pages.load("simpleTest.html")
>+    driver.pinned_scripts = {}
>+    expected = []
>+    expected.append(driver.pin_script("return arguments[0];").id)
>+    expected.append(driver.pin_script("return 'cheese';").id)
>+    expected.append(driver.pin_script("return 42;").id)
>+
>+    result = driver.get_pinned_scripts()
>+    assert expected == result
>+
>+
>+def test_should_allow_scripts_to_be_unpinned(driver, pages):
>+    pages.load("simpleTest.html")
>+    driver.pinned_scripts = {}
>+    cheese = driver.pin_script("return 'cheese';")
>+    driver.unpin(cheese)
>+    results = driver.get_pinned_scripts()
>+    assert cheese not in results
>+
>+
>+def test_calling_unpinned_script_causes_error(driver, pages):
>+    pages.load("simpleTest.html")
>+    cheese = driver.pin_script("return 'brie';")
>+    driver.unpin(cheese)
>+    with pytest.raises(JavascriptException):
>+        driver.execute_script(cheese)
>diff --git a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/select_class_tests.py b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/select_class_tests.py
>index 52b7d9b98e1c..31526ad42cd2 100644
>--- a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/select_class_tests.py
>+++ b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/select_class_tests.py
>@@ -91,20 +91,20 @@ def testSelectByVisibleTextSingle(driver, pages):
>             assert sel.first_selected_option.text == select['values'][x]
> 
> 
>-@pytest.mark.xfail_chrome(
>-    reason='https://bugs.chromium.org/p/chromedriver/issues/detail?id=822')
>-@pytest.mark.xfail_chromiumedge(
>-    reason='https://bugs.chromium.org/p/chromedriver/issues/detail?id=822')
>-@pytest.mark.xfail_safari
>-def testSelectByVisibleTextShouldNormalizeSpaces(driver, pages):
>-    pages.load("formPage.html")
>-
>-    for select in [singleSelectValuesWithSpaces]:
>-        sel = Select(driver.find_element(By.NAME, select['name']))
>-        for x in range(len(select['values'])):
>-            print(select['values'][x])
>-            sel.select_by_visible_text(select['values'][x])
>-            assert sel.first_selected_option.text == select['values'][x]
>+# @pytest.mark.xfail_chrome(
>+#     reason='https://bugs.chromium.org/p/chromedriver/issues/detail?id=822')
>+# @pytest.mark.xfail_chromiumedge(
>+#     reason='https://bugs.chromium.org/p/chromedriver/issues/detail?id=822')
>+# @pytest.mark.xfail_safari
>+# def testSelectByVisibleTextShouldNormalizeSpaces(driver, pages):
>+#     pages.load("formPage.html")
>+
>+#     for select in [singleSelectValuesWithSpaces]:
>+#         sel = Select(driver.find_element(By.NAME, select['name']))
>+#         for x in range(len(select['values'])):
>+#             print(select['values'][x])
>+#             sel.select_by_visible_text(select['values'][x])
>+#             assert sel.first_selected_option.text == select['values'][x]
> 
> 
> @pytest.mark.xfail_firefox(reason='https://bugzilla.mozilla.org/show_bug.cgi?id=1429403')
>diff --git a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/window_tests.py b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/window_tests.py
>index 85eb247b2986..98509b141525 100644
>--- a/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/window_tests.py
>+++ b/WebDriverTests/imported/selenium/py/test/selenium/webdriver/common/window_tests.py
>@@ -14,30 +14,30 @@
> # KIND, either express or implied.  See the License for the
> # specific language governing permissions and limitations
> # under the License.
>-import os
>+
> import pytest
> 
> from selenium.common.exceptions import WebDriverException
> from selenium.webdriver.support.wait import WebDriverWait
> 
> 
>-@pytest.mark.xfail_ie
>-@pytest.mark.xfail_chromiumedge(reason="Fails on Travis")
>-@pytest.mark.xfail_firefox(reason="Fails on Travis")
>-@pytest.mark.xfail_remote(reason="Fails on Travis")
>-def testShouldMaximizeTheWindow(driver):
>-    resize_timeout = 5
>-    wait = WebDriverWait(driver, resize_timeout)
>-    old_size = driver.get_window_size()
>-    driver.set_window_size(200, 200)
>-    wait.until(
>-        lambda dr: dr.get_window_size() != old_size if old_size["width"] != 200 and old_size["height"] != 200 else True)
>-    size = driver.get_window_size()
>-    driver.maximize_window()
>-    wait.until(lambda dr: dr.get_window_size() != size)
>-    new_size = driver.get_window_size()
>-    assert new_size["width"] > size["width"]
>-    assert new_size["height"] > size["height"]
>+# @pytest.mark.xfail_ie
>+# @pytest.mark.xfail_chromiumedge(reason="Fails on Travis")
>+# @pytest.mark.xfail_firefox(reason="Fails on Travis")
>+# @pytest.mark.xfail_remote(reason="Fails on Travis")
>+# def testShouldMaximizeTheWindow(driver):
>+#     resize_timeout = 5
>+#     wait = WebDriverWait(driver, resize_timeout)
>+#     old_size = driver.get_window_size()
>+#     driver.set_window_size(200, 200)
>+#     wait.until(
>+#         lambda dr: dr.get_window_size() != old_size if old_size["width"] != 200 and old_size["height"] != 200 else True)
>+#     size = driver.get_window_size()
>+#     driver.maximize_window()
>+#     wait.until(lambda dr: dr.get_window_size() != size)
>+#     new_size = driver.get_window_size()
>+#     assert new_size["width"] > size["width"]
>+#     assert new_size["height"] > size["height"]
> 
> 
> def test_should_get_the_size_of_the_current_window(driver):
>@@ -112,37 +112,37 @@ def test_should_set_the_rect_of_the_current_window(driver):
>     assert new_rect.get('height') == target_height
> 
> 
>-@pytest.mark.xfail_safari(raises=WebDriverException,
>-                          reason='Fullscreen command not implemented')
>-@pytest.mark.skipif(os.environ.get('TRAVIS') == 'true',
>-                    reason='Fullscreen command causes Travis to hang')
>-@pytest.mark.no_driver_after_test
>-def test_should_fullscreen_the_current_window(driver):
>-    start_width = driver.execute_script('return window.innerWidth;')
>-    start_height = driver.execute_script('return window.innerHeight;')
>+# @pytest.mark.xfail_safari(raises=WebDriverException,
>+#                           reason='Fullscreen command not implemented')
>+# @pytest.mark.skipif(os.environ.get('TRAVIS') == 'true',
>+#                     reason='Fullscreen command causes Travis to hang')
>+# @pytest.mark.no_driver_after_test
>+# def test_should_fullscreen_the_current_window(driver):
>+#     start_width = driver.execute_script('return window.innerWidth;')
>+#     start_height = driver.execute_script('return window.innerHeight;')
> 
>-    driver.fullscreen_window()
>+#     driver.fullscreen_window()
> 
>-    WebDriverWait(driver, 2)\
>-        .until(lambda d: driver.execute_script('return window.innerWidth;') > start_width)
>+#     WebDriverWait(driver, 2)\
>+#         .until(lambda d: driver.execute_script('return window.innerWidth;') > start_width)
> 
>-    end_width = driver.execute_script('return window.innerWidth;')
>-    end_height = driver.execute_script('return window.innerHeight;')
>+#     end_width = driver.execute_script('return window.innerWidth;')
>+#     end_height = driver.execute_script('return window.innerHeight;')
> 
>-    driver.quit()  # Kill driver so we aren't running fullscreen after
>+#     driver.quit()  # Kill driver so we aren't running fullscreen after
> 
>-    assert end_width > start_width
>-    assert end_height > start_height
>+#     assert end_width > start_width
>+#     assert end_height > start_height
> 
> 
>-@pytest.mark.xfail_safari(raises=WebDriverException,
>-                          reason='Minimize command not implemented')
>-@pytest.mark.skipif(os.environ.get('TRAVIS') == 'true',
>-                    reason='Minimize command causes Travis to hang')
>-@pytest.mark.no_driver_after_test
>-def test_should_minimize_the_current_window(driver):
>-    driver.minimize_window()
>-    minimized = driver.execute_script('return document.hidden;')
>-    driver.quit()  # Kill driver so we aren't running minimized after
>-
>-    assert minimized is True
>+# @pytest.mark.xfail_safari(raises=WebDriverException,
>+#                           reason='Minimize command not implemented')
>+# @pytest.mark.skipif(os.environ.get('TRAVIS') == 'true',
>+#                     reason='Minimize command causes Travis to hang')
>+# @pytest.mark.no_driver_after_test
>+# def test_should_minimize_the_current_window(driver):
>+#     driver.minimize_window()
>+#     minimized = driver.execute_script('return document.hidden;')
>+#     driver.quit()  # Kill driver so we aren't running minimized after
>+
>+#     assert minimized is True
>diff --git a/WebDriverTests/imported/w3c/importer.json b/WebDriverTests/imported/w3c/importer.json
>index f400ef5a3957..eaa801872305 100644
>--- a/WebDriverTests/imported/w3c/importer.json
>+++ b/WebDriverTests/imported/w3c/importer.json
>@@ -1,6 +1,6 @@
> {
>     "repository": "https://github.com/w3c/web-platform-tests.git",
>-    "revision": "b57da97fc05e5440ae675027dd45a26be48e2dbd",
>+    "revision": "eb8bdce552a2a9b10010f7755ed9d8d0773d548e",
>     "paths_to_import": [
>         "tools/webdriver",
>         "tools/wptrunner",
>diff --git a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/__init__.py b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/__init__.py
>index d860b9ea2533..a81751407e70 100644
>--- a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/__init__.py
>+++ b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/__init__.py
>@@ -6,6 +6,7 @@ from .client import (
>     Find,
>     Frame,
>     Session,
>+    ShadowRoot,
>     Timeouts,
>     Window)
> from .error import (
>@@ -34,3 +35,5 @@ from .error import (
>     UnknownMethodException,
>     UnsupportedOperationException,
>     WebDriverException)
>+from .bidi import (
>+    BidiSession)
>diff --git a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/bidi.py b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/bidi.py
>new file mode 100644
>index 000000000000..0bcd489cd35e
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/bidi.py
>@@ -0,0 +1,56 @@
>+import copy
>+import websockets
>+
>+from . import client
>+
>+class BidiSession(client.Session):
>+    def __init__(self,
>+                 host,
>+                 port,
>+                 url_prefix="/",
>+                 capabilities=None,
>+                 extension=None):
>+        """
>+        Add a capability of "webSocketUrl": True to enable
>+        Bidirectional connection in session creation.
>+        """
>+        self.websocket_transport = None
>+        capabilities = self._enable_websocket(capabilities)
>+        super().__init__(host, port, url_prefix, capabilities, extension)
>+
>+    def _enable_websocket(self, caps):
>+        if caps:
>+            caps.setdefault("alwaysMatch", {}).update({"webSocketUrl": True})
>+        else:
>+            caps = {"alwaysMatch": {"webSocketUrl": True}}
>+        return caps
>+
>+    def match(self, capabilities):
>+        """Expensive match to see if capabilities is the same as previously
>+        requested capabilities if websocket would be enabled.
>+
>+        :return Boolean.
>+        """
>+        caps = copy.deepcopy(capabilities)
>+        caps = self._enable_websocket(caps)
>+        return super().match(caps)
>+
>+    async def start(self):
>+        """Start a new WebDriver Bidirectional session
>+        with websocket connected.
>+
>+        :return: Dictionary with `capabilities` and `sessionId`.
>+        """
>+        value = super().start()
>+
>+        if not self.websocket_transport or not self.websocket_transport.open:
>+            self.websocket_transport = await websockets.connect(self.capabilities["webSocketUrl"])
>+        return value
>+
>+    async def end(self):
>+        """Close websocket connection first before closing session.
>+        """
>+        if self.websocket_transport:
>+            await self.websocket_transport.close()
>+            self.websocket_transport = None
>+        super().end()
>diff --git a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/bidi/__init__.py b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/bidi/__init__.py
>new file mode 100644
>index 000000000000..e7c56332f902
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/bidi/__init__.py
>@@ -0,0 +1,3 @@
>+# flake8: noqa
>+
>+from .client import BidiSession
>diff --git a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/bidi/client.py b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/bidi/client.py
>new file mode 100644
>index 000000000000..4309a25e3873
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/bidi/client.py
>@@ -0,0 +1,393 @@
>+import asyncio
>+import functools
>+import json
>+import logging
>+import sys
>+from collections import defaultdict
>+from typing import Any, Awaitable, Callable, Coroutine, List, Optional, Mapping, MutableMapping
>+from urllib.parse import urljoin, urlparse
>+
>+import websockets
>+
>+
>+logger = logging.getLogger("webdriver.bidi")
>+
>+
>+class BidiException(Exception):
>+    def __init__(self, err: str, msg: str, stack: Optional[str] = None):
>+        self.err = err
>+        self.msg = msg
>+        self.stack = stack
>+
>+
>+def get_running_loop() -> asyncio.AbstractEventLoop:
>+    if sys.version_info >= (3, 7):
>+        return asyncio.get_running_loop()
>+    # Unlike the above, this will actually create an event loop
>+    # if there isn't one; hopefully running tests in Python >= 3.7
>+    # will allow us to catch any behaviour difference
>+    return asyncio.get_event_loop()
>+
>+
>+class BidiSession:
>+    """A WebDriver BiDi session.
>+
>+    This is the main representation of a BiDi session and provides the
>+    interface for running commands in the session, and for attaching
>+    event handlers to the session. For example:
>+
>+    async def on_log(data):
>+        print(data)
>+
>+    session = BidiSession("ws://localhost:4445", capabilities)
>+    session.add_event_listener("log.entryAdded", on_log)
>+    await session.start()
>+    await session.subscribe("log.entryAdded")
>+    # Do some stuff with the session
>+    session.end()
>+
>+    If the session id is provided it's assumed that the underlying
>+    WebDriver session was already created, and the WebSocket URL was
>+    taken from the new session response. If no session id is provided, it's
>+    assumed that a BiDi-only session should be created when start() is called.
>+
>+    It can also be used as a context manager, with the WebSocket transport
>+    implictly being created when the context is entered, and closed when
>+    the context is exited.
>+
>+    :param websocket_url: WebSockets URL on which to connect to the session.
>+                          This excludes any path component.
>+    :param session_id: String id of existing HTTP session
>+    :param capabilities: Capabilities response of existing session
>+    :param requested_capabilities: Dictionary representing the capabilities request.
>+
>+    """
>+
>+    def __init__(self,
>+                 websocket_url: str,
>+                 session_id: Optional[str] = None,
>+                 capabilities: Optional[Mapping[str, Any]] = None,
>+                 requested_capabilities: Optional[Mapping[str, Any]] = None,
>+                 loop: Optional[asyncio.AbstractEventLoop] = None):
>+        self.transport: Optional[Transport] = None
>+
>+        # The full URL for a websocket looks like
>+        # ws://<host>:<port>/session when we're creating a session and
>+        # ws://<host>:<port>/session/<sessionid> when we're connecting to an existing session.
>+        # To be user friendly, handle the case where the class was created with either a
>+        # full URL including the path, and also the case where just a server url is passed in.
>+        parsed_url = urlparse(websocket_url)
>+        if parsed_url.path == "" or parsed_url.path == "/":
>+            if session_id is None:
>+                websocket_url = urljoin(websocket_url, "session")
>+            else:
>+                websocket_url = urljoin(websocket_url, f"session/{session_id}")
>+        else:
>+            if session_id is not None:
>+                if parsed_url.path != f"/session/{session_id}":
>+                    raise ValueError(f"WebSocket URL {session_id} doesn't match session id")
>+            else:
>+                if parsed_url.path != "/session":
>+                    raise ValueError(f"WebSocket URL {session_id} doesn't match session url")
>+
>+        if session_id is None and capabilities is not None:
>+            raise ValueError("Tried to create BiDi-only session with existing capabilities")
>+
>+        self.websocket_url = websocket_url
>+        self.requested_capabilities = requested_capabilities
>+        self.capabilities = capabilities
>+        self.session_id = session_id
>+
>+        self.command_id = 0
>+        self.pending_commands: MutableMapping[int, "asyncio.Future[Any]"] = {}
>+        self.event_listeners: MutableMapping[Optional[str], List[Callable[[str, Mapping[str, Any]], Any]]] = defaultdict(list)
>+
>+        # Modules.
>+        # For each module, have a property representing that module
>+        self.session = Session(self)
>+
>+        if loop is None:
>+            loop = get_running_loop()
>+        self.loop = loop
>+
>+    @classmethod
>+    def from_http(cls,
>+                  session_id: str,
>+                  capabilities: Mapping[str, Any],
>+                  loop: Optional[asyncio.AbstractEventLoop] = None) -> "BidiSession":
>+        """Create a BiDi session from an existing HTTP session
>+
>+        :param session_id: String id of the session
>+        :param capabilities: Capabilities returned in the New Session HTTP response."""
>+        websocket_url = capabilities.get("webSocketUrl")
>+        if websocket_url is None:
>+            raise ValueError("No webSocketUrl found in capabilities")
>+        if not isinstance(websocket_url, str):
>+            raise ValueError("webSocketUrl is not a string")
>+        return cls(websocket_url, session_id=session_id, capabilities=capabilities, loop=loop)
>+
>+    @classmethod
>+    def bidi_only(cls,
>+                  websocket_url: str,
>+                  requested_capabilities: Optional[Mapping[str, Any]],
>+                  loop: Optional[asyncio.AbstractEventLoop] = None) -> "BidiSession":
>+        """Create a BiDi session where there is no existing HTTP session
>+
>+        :param webdocket_url: URL to the WebSocket server listening for BiDi connections
>+        :param requested_capabilities: Capabilities request for establishing the session."""
>+        return cls(websocket_url, requested_capabilities=requested_capabilities, loop=loop)
>+
>+    async def __aenter__(self) -> "BidiSession":
>+        await self.start()
>+        return self
>+
>+    async def __aexit__(self, *args: Any) -> None:
>+        await self.end()
>+
>+    async def start(self) -> None:
>+        """Connect to the WebDriver BiDi remote via WebSockets"""
>+        self.transport = Transport(self.websocket_url, self.on_message, loop=self.loop)
>+
>+        if self.session_id is None:
>+            self.session_id, self.capabilities = await self.session.new(self.requested_capabilities)
>+
>+        await self.transport.start()
>+
>+    async def send_command(self, method: str, params: Mapping[str, Any]) -> Awaitable[Mapping[str, Any]]:
>+        """Send a command to the remote server"""
>+        # this isn't threadsafe
>+        self.command_id += 1
>+        command_id = self.command_id
>+
>+        body = {
>+            "id": command_id,
>+            "method": method,
>+            "params": params
>+        }
>+        assert command_id not in self.pending_commands
>+        self.pending_commands[command_id] = self.loop.create_future()
>+        assert self.transport is not None
>+        await self.transport.send(body)
>+
>+        return self.pending_commands[command_id]
>+
>+    async def on_message(self, data: Mapping[str, Any]) -> None:
>+        """Handle a message from the remote server"""
>+        if "id" in data:
>+            # This is a command response or error
>+            future = self.pending_commands.get(data["id"])
>+            if future is None:
>+                raise ValueError(f"No pending command with id {data['id']}")
>+            if "result" in data:
>+                future.set_result(data["result"])
>+            elif "error" in data and "message" in data:
>+                assert isinstance(data["error"], str)
>+                assert isinstance(data["message"], str)
>+                future.set_exception(BidiException(data["error"],
>+                                                   data["message"],
>+                                                   data.get("stacktrace")))
>+            else:
>+                raise ValueError(f"Unexpected message: {data!r}")
>+        elif "method" in data and "params" in data:
>+            # This is an event
>+            method = data["method"]
>+            listeners = self.event_listeners.get(method, [])
>+            if not listeners:
>+                listeners = self.event_listeners.get(None, [])
>+            for listener in listeners:
>+                await listener(method, data["params"])
>+        else:
>+            raise ValueError(f"Unexpected message: {data!r}")
>+
>+    async def end(self) -> None:
>+        """Close websocket connection."""
>+        assert self.transport is not None
>+        await self.transport.end()
>+
>+    def add_event_listener(self,
>+                           name: Optional[str],
>+                           fn: Callable[[str, Mapping[str, Any]], Awaitable[Any]]) -> None:
>+        """Add a listener for the event with a given name.
>+
>+        If name is None, the listener is called for all messages that are not otherwise
>+        handled.
>+
>+        :param name: Name of event to listen for or None to register a default handler
>+        :param fn: Async callback function that receives event data
>+        """
>+        self.event_listeners[name].append(fn)
>+
>+
>+class Transport:
>+    """Low level message handler for the WebSockets connection"""
>+    def __init__(self, url: str,
>+                 msg_handler: Callable[[Mapping[str, Any]], Coroutine[Any, Any, None]],
>+                 loop: Optional[asyncio.AbstractEventLoop] = None):
>+        self.url = url
>+        self.connection: Optional[websockets.WebSocketClientProtocol] = None
>+        self.msg_handler = msg_handler
>+        self.send_buf: List[Mapping[str, Any]] = []
>+
>+        if loop is None:
>+            loop = get_running_loop()
>+        self.loop = loop
>+
>+        self.read_message_task: Optional[asyncio.Task[Any]] = None
>+
>+    async def start(self) -> None:
>+        self.connection = await websockets.client.connect(self.url)
>+        self.read_message_task = self.loop.create_task(self.read_messages())
>+
>+        for msg in self.send_buf:
>+            await self._send(self.connection, msg)
>+
>+    async def send(self, data: Mapping[str, Any]) -> None:
>+        if self.connection is not None:
>+            await self._send(self.connection, data)
>+        else:
>+            self.send_buf.append(data)
>+
>+    @staticmethod
>+    async def _send(connection: websockets.WebSocketClientProtocol, data: Mapping[str, Any]) -> None:
>+        msg = json.dumps(data)
>+        logger.debug("â %s", msg)
>+        await connection.send(msg)
>+
>+    async def handle(self, msg: str) -> None:
>+        logger.debug("â %s", msg)
>+        data = json.loads(msg)
>+        await self.msg_handler(data)
>+
>+    async def end(self) -> None:
>+        if self.connection:
>+            await self.connection.close()
>+            self.connection = None
>+
>+    async def read_messages(self) -> None:
>+        assert self.connection is not None
>+        async for msg in self.connection:
>+            if not isinstance(msg, str):
>+                raise ValueError("Got a binary message")
>+            await self.handle(msg)
>+
>+
>+class command:
>+    """Decorator for implementing bidi commands
>+
>+    Implementing a command involves specifying an async function that
>+    builds the parameters to the command. The decorator arranges those
>+    parameters to be turned into a send_command call, using the class
>+    and method names to determine the method in the call.
>+
>+    Commands decorated in this way don't return a future, but await
>+    the actual response. In some cases it can be useful to
>+    post-process this response before returning it to the client. This
>+    can be done by specifying a second decorated method like
>+    @command_name.result. That method will then be called once the
>+    result of the original command is known, and the return value of
>+    the method used as the response of the command.
>+
>+    So for an example, if we had a command test.testMethod, which
>+    returned a result which we want to convert to a TestResult type,
>+    the implementation might look like:
>+
>+    class Test(BidiModule):
>+        @command
>+        def test_method(self, test_data=None):
>+            return {"testData": test_data}
>+
>+       @test_method.result
>+       def convert_test_method_result(self, result):
>+           return TestData(**result)
>+    """
>+
>+    def __init__(self, fn: Callable[..., Mapping[str, Any]]):
>+        self.params_fn = fn
>+        self.result_fn: Optional[Callable[..., Any]] = None
>+
>+    def result(self, fn: Callable[[Any, MutableMapping[str, Any]], Mapping[str, Any]]) -> None:
>+        self.result_fn = fn
>+
>+    def __set_name__(self, owner: Any, name: str) -> None:
>+        # This is called when the class is created
>+        # see https://docs.python.org/3/reference/datamodel.html#object.__set_name__
>+        params_fn = self.params_fn
>+        result_fn = self.result_fn
>+
>+        @functools.wraps(params_fn)
>+        async def inner(self: Any, **kwargs: Any) -> Any:
>+            params = params_fn(self, **kwargs)
>+
>+            # Convert the classname and the method name to a bidi command name
>+            mod_name = owner.__name__.lower()
>+            if hasattr(owner, "prefix"):
>+                mod_name = f"{owner.prefix}:{mod_name}"
>+            cmd_name = f"{mod_name}.{to_camelcase(name)}"
>+
>+            future = await self.session.send_command(cmd_name, params)
>+            result = await future
>+
>+            if result_fn is not None:
>+                # Convert the result if we have a conversion function defined
>+                result = result_fn(self, result)
>+            return result
>+
>+        # Overwrite the method on the owner class with the wrapper
>+        setattr(owner, name, inner)
>+
>+    def __call__(*args: Any, **kwargs: Any) -> Awaitable[Any]:
>+        # This isn't really used, but mypy doesn't understand __set_name__
>+        pass
>+
>+
>+def to_camelcase(name: str) -> str:
>+    """Convert a python style method name foo_bar to a BiDi command name fooBar"""
>+    parts = name.split("_")
>+    parts[0] = parts[0].lower()
>+    for i in range(1, len(parts)):
>+        parts[i] = parts[i].title()
>+    return "".join(parts)
>+
>+
>+class BidiModule:
>+    def __init__(self, session: BidiSession):
>+        self.session = session
>+
>+
>+class Session(BidiModule):
>+    @command
>+    def new(self, capabilities: Mapping[str, Any]) -> Mapping[str, Mapping[str, Any]]:
>+        return {"capabilities": capabilities}
>+
>+    @new.result
>+    def _new(self, result: Mapping[str, Any]) -> Any:
>+        return result.get("session_id"), result.get("capabilities", {})
>+
>+    @command
>+    def subscribe(self,
>+                  events: Optional[List[str]] = None,
>+                  contexts: Optional[List[str]] = None) -> Mapping[str, Any]:
>+        params: MutableMapping[str, Any] = {"events": events if events is not None else []}
>+        if contexts is not None:
>+            params["contexts"] = contexts
>+        return params
>+
>+    @command
>+    def unsubscribe(self,
>+                    events: Optional[List[str]] = None,
>+                    contexts: Optional[List[str]] = None) -> Mapping[str, Any]:
>+        params: MutableMapping[str, Any] = {"events": events if events is not None else []}
>+        if contexts is not None:
>+            params["contexts"] = contexts
>+        return params
>+
>+
>+class Test(BidiModule):
>+    """Very temporary module that does nothing, except demonstrate a vendor prefix and
>+    provide a way to work with Gecko's current skeleton implementation."""
>+
>+    prefix = "moz"
>+
>+    @command
>+    def test_method(self, **kwargs):
>+        return kwargs
>diff --git a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/client.py b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/client.py
>index f4e3c763795e..2c7b1c5dbeb1 100644
>--- a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/client.py
>+++ b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/client.py
>@@ -1,9 +1,9 @@
> from . import error
> from . import protocol
> from . import transport
>+from .bidi.client import BidiSession
> 
>-from six import string_types
>-from six.moves.urllib import parse as urlparse
>+from urllib import parse as urlparse
> 
> 
> def command(func):
>@@ -116,14 +116,49 @@ class ActionSequence(object):
>     def _key_action(self, subtype, value):
>         self._actions.append({"type": subtype, "value": value})
> 
>-    def _pointer_action(self, subtype, button):
>-        self._actions.append({"type": subtype, "button": button})
>+    def _pointer_action(self, subtype, button=None, x=None, y=None, duration=None, origin=None, width=None,
>+                        height=None, pressure=None, tangential_pressure=None, tilt_x=None,
>+                        tilt_y=None, twist=None, altitude_angle=None, azimuth_angle=None):
>+        action = {
>+            "type": subtype
>+        }
>+        if button is not None:
>+            action["button"] = button
>+        if x is not None:
>+            action["x"] = x
>+        if y is not None:
>+            action["y"] = y
>+        if duration is not None:
>+            action["duration"] = duration
>+        if origin is not None:
>+            action["origin"] = origin
>+        if width is not None:
>+            action["width"] = width
>+        if height is not None:
>+            action["height"] = height
>+        if pressure is not None:
>+            action["pressure"] = pressure
>+        if tangential_pressure is not None:
>+            action["tangentialPressure"] = tangential_pressure
>+        if tilt_x is not None:
>+            action["tiltX"] = tilt_x
>+        if tilt_y is not None:
>+            action["tiltY"] = tilt_y
>+        if twist is not None:
>+            action["twist"] = twist
>+        if altitude_angle is not None:
>+            action["altitudeAngle"] = altitude_angle
>+        if azimuth_angle is not None:
>+            action["azimuthAngle"] = azimuth_angle
>+        self._actions.append(action)
> 
>     def pause(self, duration):
>         self._actions.append({"type": "pause", "duration": duration})
>         return self
> 
>-    def pointer_move(self, x, y, duration=None, origin=None):
>+    def pointer_move(self, x, y, duration=None, origin=None, width=None, height=None,
>+                     pressure=None, tangential_pressure=None, tilt_x=None, tilt_y=None,
>+                     twist=None, altitude_angle=None, azimuth_angle=None):
>         """Queue a pointerMove action.
> 
>         :param x: Destination x-axis coordinate of pointer in CSS pixels.
>@@ -133,16 +168,10 @@ class ActionSequence(object):
>         :param origin: Origin of coordinates, either "viewport", "pointer" or
>                        an Element. If None, remote end defaults to "viewport".
>         """
>-        action = {
>-            "type": "pointerMove",
>-            "x": x,
>-            "y": y
>-        }
>-        if duration is not None:
>-            action["duration"] = duration
>-        if origin is not None:
>-            action["origin"] = origin
>-        self._actions.append(action)
>+        self._pointer_action("pointerMove", x=x, y=y, duration=duration, origin=origin,
>+                             width=width, height=height, pressure=pressure,
>+                             tangential_pressure=tangential_pressure, tilt_x=tilt_x, tilt_y=tilt_y,
>+                             twist=twist, altitude_angle=altitude_angle, azimuth_angle=azimuth_angle)
>         return self
> 
>     def pointer_up(self, button=0):
>@@ -151,16 +180,21 @@ class ActionSequence(object):
>         :param button: Pointer button to perform action with.
>                        Default: 0, which represents main device button.
>         """
>-        self._pointer_action("pointerUp", button)
>+        self._pointer_action("pointerUp", button=button)
>         return self
> 
>-    def pointer_down(self, button=0):
>+    def pointer_down(self, button=0, width=None, height=None, pressure=None,
>+                     tangential_pressure=None, tilt_x=None, tilt_y=None,
>+                     twist=None, altitude_angle=None, azimuth_angle=None):
>         """Queue a pointerDown action for `button`.
> 
>         :param button: Pointer button to perform action with.
>                        Default: 0, which represents main device button.
>         """
>-        self._pointer_action("pointerDown", button)
>+        self._pointer_action("pointerDown", button=button, width=width, height=height,
>+                             pressure=pressure, tangential_pressure=tangential_pressure,
>+                             tilt_x=tilt_x, tilt_y=tilt_y, twist=twist, altitude_angle=altitude_angle,
>+                             azimuth_angle=azimuth_angle)
>         return self
> 
>     def click(self, element=None, button=0):
>@@ -273,19 +307,22 @@ class Window(object):
> 
>         return handles
> 
>-    @property
>+    # The many "type: ignore" comments here and below are to silence mypy's
>+    # "Decorated property not supported" error, which is due to a limitation
>+    # in mypy, see https://github.com/python/mypy/issues/1362.
>+    @property  # type: ignore
>     @command
>     def rect(self):
>         return self.session.send_session_command("GET", "window/rect")
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def size(self):
>         """Gets the window size as a tuple of `(width, height)`."""
>         rect = self.rect
>         return (rect["width"], rect["height"])
> 
>-    @size.setter
>+    @size.setter  # type: ignore
>     @command
>     def size(self, new_size):
>         """Set window size by passing a tuple of `(width, height)`."""
>@@ -293,14 +330,14 @@ class Window(object):
>         body = {"width": width, "height": height}
>         self.session.send_session_command("POST", "window/rect", body)
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def position(self):
>         """Gets the window position as a tuple of `(x, y)`."""
>         rect = self.rect
>         return (rect["x"], rect["y"])
> 
>-    @position.setter
>+    @position.setter  # type: ignore
>     @command
>     def position(self, new_position):
>         """Set window position by passing a tuple of `(x, y)`."""
>@@ -338,6 +375,42 @@ class Frame(object):
>         return cls(uuid, session)
> 
> 
>+class ShadowRoot(object):
>+    identifier = "shadow-6066-11e4-a52e-4f735466cecf"
>+
>+    def __init__(self, session, id):
>+        """
>+        Construct a new shadow root representation.
>+
>+        :param id: Shadow root UUID which must be unique across
>+            all browsing contexts.
>+        :param session: Current ``webdriver.Session``.
>+        """
>+        self.id = id
>+        self.session = session
>+
>+    @classmethod
>+    def from_json(cls, json, session):
>+        uuid = json[ShadowRoot.identifier]
>+        return cls(uuid, session)
>+
>+    def send_shadow_command(self, method, uri, body=None):
>+        url = "shadow/{}/{}".format(self.id, uri)
>+        return self.session.send_session_command(method, url, body)
>+
>+    @command
>+    def find_element(self, strategy, selector):
>+        body = {"using": strategy,
>+                "value": selector}
>+        return self.send_shadow_command("POST", "element", body)
>+
>+    @command
>+    def find_elements(self, strategy, selector):
>+        body = {"using": strategy,
>+                "value": selector}
>+        return self.send_shadow_command("POST", "elements", body)
>+
>+
> class Find(object):
>     def __init__(self, session):
>         self.session = session
>@@ -365,7 +438,7 @@ class Cookies(object):
>         cookie = {"name": name,
>                   "value": None}
> 
>-        if isinstance(name, string_types):
>+        if isinstance(name, str):
>             cookie["value"] = value
>         elif hasattr(value, "value"):
>             cookie["value"] = value.value
>@@ -384,12 +457,12 @@ class UserPrompt(object):
>     def accept(self):
>         self.session.send_session_command("POST", "alert/accept")
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def text(self):
>         return self.session.send_session_command("GET", "alert/text")
> 
>-    @text.setter
>+    @text.setter  # type: ignore
>     @command
>     def text(self, value):
>         body = {"text": value}
>@@ -401,8 +474,16 @@ class Session(object):
>                  host,
>                  port,
>                  url_prefix="/",
>+                 enable_bidi=False,
>                  capabilities=None,
>                  extension=None):
>+
>+        if enable_bidi:
>+            if capabilities is not None:
>+                capabilities.setdefault("alwaysMatch", {}).update({"webSocketUrl": True})
>+            else:
>+                capabilities = {"alwaysMatch": {"webSocketUrl": True}}
>+
>         self.transport = transport.HTTPWireProtocol(host, port, url_prefix)
>         self.requested_capabilities = capabilities
>         self.capabilities = None
>@@ -410,6 +491,8 @@ class Session(object):
>         self.timeouts = None
>         self.window = None
>         self.find = None
>+        self.enable_bidi = enable_bidi
>+        self.bidi_session = None
>         self.extension = None
>         self.extension_cls = extension
> 
>@@ -436,6 +519,9 @@ class Session(object):
>     def __del__(self):
>         self.end()
> 
>+    def match(self, capabilities):
>+        return self.requested_capabilities == capabilities
>+
>     def start(self):
>         """Start a new WebDriver session.
> 
>@@ -458,6 +544,14 @@ class Session(object):
>         self.session_id = value["sessionId"]
>         self.capabilities = value["capabilities"]
> 
>+        if "webSocketUrl" in self.capabilities:
>+            self.bidi_session = BidiSession.from_http(self.session_id,
>+                                                      self.capabilities)
>+        elif self.enable_bidi:
>+            self.end()
>+            raise error.SessionNotCreatedException(
>+                "Requested bidi session, but webSocketUrl capability not found")
>+
>         if self.extension_cls:
>             self.extension = self.extension_cls(self)
> 
>@@ -470,7 +564,7 @@ class Session(object):
> 
>         try:
>             self.send_command("DELETE", "session/%s" % self.session_id)
>-        except error.InvalidSessionIdException:
>+        except (OSError, error.InvalidSessionIdException):
>             pass
>         finally:
>             self.session_id = None
>@@ -545,12 +639,12 @@ class Session(object):
>         url = urlparse.urljoin("session/%s/" % self.session_id, uri)
>         return self.send_command(method, url, body, timeout)
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def url(self):
>         return self.send_session_command("GET", "url")
> 
>-    @url.setter
>+    @url.setter  # type: ignore
>     @command
>     def url(self, url):
>         if urlparse.urlsplit(url).netloc is None:
>@@ -570,12 +664,12 @@ class Session(object):
>     def refresh(self):
>         return self.send_session_command("POST", "refresh")
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def title(self):
>         return self.send_session_command("GET", "title")
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def source(self):
>         return self.send_session_command("GET", "source")
>@@ -587,12 +681,12 @@ class Session(object):
> 
>         return value["handle"]
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def window_handle(self):
>         return self.send_session_command("GET", "window")
> 
>-    @window_handle.setter
>+    @window_handle.setter  # type: ignore
>     @command
>     def window_handle(self, handle):
>         body = {"handle": handle}
>@@ -608,12 +702,12 @@ class Session(object):
> 
>         return self.send_session_command("POST", url, body)
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def handles(self):
>         return self.send_session_command("GET", "window/handles")
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def active_element(self):
>         return self.send_session_command("GET", "element/active")
>@@ -683,7 +777,6 @@ class Session(object):
>     def screenshot(self):
>         return self.send_session_command("GET", "screenshot")
> 
>-
> class Element(object):
>     """
>     Representation of a web element.
>@@ -742,12 +835,12 @@ class Element(object):
>     def send_keys(self, text):
>         return self.send_element_command("POST", "value", {"text": text})
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def text(self):
>         return self.send_element_command("GET", "text")
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def name(self):
>         return self.send_element_command("GET", "name")
>@@ -756,12 +849,12 @@ class Element(object):
>     def style(self, property_name):
>         return self.send_element_command("GET", "css/%s" % property_name)
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def rect(self):
>         return self.send_element_command("GET", "rect")
> 
>-    @property
>+    @property  # type: ignore
>     @command
>     def selected(self):
>         return self.send_element_command("GET", "selected")
>@@ -770,6 +863,11 @@ class Element(object):
>     def screenshot(self):
>         return self.send_element_command("GET", "screenshot")
> 
>+    @property  # type: ignore
>+    @command
>+    def shadow_root(self):
>+        return self.send_element_command("GET", "shadow")
>+
>     @command
>     def attribute(self, name):
>         return self.send_element_command("GET", "attribute/%s" % name)
>diff --git a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/error.py b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/error.py
>index 8379656d73dd..a413a950d48e 100644
>--- a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/error.py
>+++ b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/error.py
>@@ -1,12 +1,17 @@
> import collections
> import json
> 
>-from six import itervalues
>+from typing import ClassVar, DefaultDict, Type
> 
> 
> class WebDriverException(Exception):
>-    http_status = None
>-    status_code = None
>+    # The status_code class variable is used to map the JSON Error Code (see
>+    # https://w3c.github.io/webdriver/#errors) to a WebDriverException subclass.
>+    # However, http_status need not match, and both are set as instance
>+    # variables, shadowing the class variables. TODO: Match on both http_status
>+    # and status_code and let these be class variables only.
>+    http_status = None  # type: ClassVar[int]
>+    status_code = None  # type: ClassVar[str]
> 
>     def __init__(self, http_status=None, status_code=None, message=None, stacktrace=None):
>         super(WebDriverException, self)
>@@ -34,6 +39,11 @@ class WebDriverException(Exception):
>         return message
> 
> 
>+class DetachedShadowRootException(WebDriverException):
>+    http_status = 404
>+    status_code = "detached shadow root"
>+
>+
> class ElementClickInterceptedException(WebDriverException):
>     http_status = 400
>     status_code = "element click intercepted"
>@@ -114,6 +124,11 @@ class NoSuchFrameException(WebDriverException):
>     status_code = "no such frame"
> 
> 
>+class NoSuchShadowRootException(WebDriverException):
>+    http_status = 404
>+    status_code = "no such shadow root"
>+
>+
> class NoSuchWindowException(WebDriverException):
>     http_status = 404
>     status_code = "no such window"
>@@ -209,7 +224,7 @@ def get(error_code):
>     return _errors.get(error_code, WebDriverException)
> 
> 
>-_errors = collections.defaultdict()
>-for item in list(itervalues(locals())):
>+_errors: DefaultDict[str, Type[WebDriverException]] = collections.defaultdict()
>+for item in list(locals().values()):
>     if type(item) == type and issubclass(item, WebDriverException):
>         _errors[item.status_code] = item
>diff --git a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/protocol.py b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/protocol.py
>index c811f6f26db7..e71e01d62083 100644
>--- a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/protocol.py
>+++ b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/protocol.py
>@@ -2,8 +2,6 @@ import json
> 
> import webdriver
> 
>-from six import iteritems
>-
> 
> """WebDriver wire protocol codecs."""
> 
>@@ -22,6 +20,8 @@ class Encoder(json.JSONEncoder):
>             return {webdriver.Frame.identifier: obj.id}
>         elif isinstance(obj, webdriver.Window):
>             return {webdriver.Frame.identifier: obj.id}
>+        elif isinstance(obj, webdriver.ShadowRoot):
>+            return {webdriver.ShadowRoot.identifier: obj.id}
>         return super(Encoder, self).default(obj)
> 
> 
>@@ -40,6 +40,8 @@ class Decoder(json.JSONDecoder):
>             return webdriver.Frame.from_json(payload, self.session)
>         elif isinstance(payload, dict) and webdriver.Window.identifier in payload:
>             return webdriver.Window.from_json(payload, self.session)
>+        elif isinstance(payload, dict) and webdriver.ShadowRoot.identifier in payload:
>+            return webdriver.ShadowRoot.from_json(payload, self.session)
>         elif isinstance(payload, dict):
>-            return {k: self.object_hook(v) for k, v in iteritems(payload)}
>+            return {k: self.object_hook(v) for k, v in payload.items()}
>         return payload
>diff --git a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/transport.py b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/transport.py
>index e836b19a158d..5a1ce289ec09 100644
>--- a/WebDriverTests/imported/w3c/tools/webdriver/webdriver/transport.py
>+++ b/WebDriverTests/imported/w3c/tools/webdriver/webdriver/transport.py
>@@ -1,10 +1,9 @@
> import json
> import select
> 
>-from six import text_type, PY3
>-from six.moves.collections_abc import Mapping
>-from six.moves.http_client import HTTPConnection
>-from six.moves.urllib import parse as urlparse
>+from http.client import HTTPConnection
>+from typing import Dict, List, Mapping, Sequence, Tuple
>+from urllib import parse as urlparse
> 
> from . import error
> 
>@@ -14,7 +13,7 @@ from . import error
> missing = object()
> 
> 
>-class ResponseHeaders(Mapping):
>+class ResponseHeaders(Mapping[str, str]):
>     """Read-only dictionary-like API for accessing response headers.
> 
>     This class:
>@@ -23,11 +22,9 @@ class ResponseHeaders(Mapping):
>       * Has case-insensitive header lookup.
>       * Always returns all header values that have the same name, separated by
>         commas.
>-
>-    It does not ensure header types (e.g. binary vs string).
>     """
>-    def __init__(self, items):
>-        self.headers_dict = {}
>+    def __init__(self, items: Sequence[Tuple[str, str]]):
>+        self.headers_dict: Dict[str, List[str]] = {}
>         for key, value in items:
>             key = key.lower()
>             if key not in self.headers_dict:
>@@ -145,15 +142,18 @@ class HTTPWireProtocol(object):
>     def close(self):
>         """Closes the current HTTP connection, if there is one."""
>         if self._conn:
>-            self._conn.close()
>+            try:
>+                self._conn.close()
>+            except OSError:
>+                # The remote closed the connection
>+                pass
>+        self._conn = None
> 
>     @property
>     def connection(self):
>         """Gets the current HTTP connection, or lazily creates one."""
>         if not self._conn:
>             conn_kwargs = {}
>-            if not PY3:
>-                conn_kwargs["strict"] = True
>             # We are not setting an HTTP timeout other than the default when the
>             # connection its created. The send method has a timeout value if needed.
>             self._conn = HTTPConnection(self.host, self.port, **conn_kwargs)
>@@ -235,7 +235,7 @@ class HTTPWireProtocol(object):
>         return Response.from_http(response, decoder=decoder, **codec_kwargs)
> 
>     def _request(self, method, uri, payload, headers=None, timeout=None):
>-        if isinstance(payload, text_type):
>+        if isinstance(payload, str):
>             payload = payload.encode("utf-8")
> 
>         if headers is None:
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/README.rst b/WebDriverTests/imported/w3c/tools/wptrunner/README.rst
>index 0adf0a94b15d..4a079c725bd6 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/README.rst
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/README.rst
>@@ -6,7 +6,6 @@ wptrunner is a harness for running the W3C `web-platform-tests testsuite`_.
> .. toctree::
>    :maxdepth: 2
> 
>-   docs/usage
>    docs/expectation
>    docs/design
>    docs/internals
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/docs/usage.rst b/WebDriverTests/imported/w3c/tools/wptrunner/docs/usage.rst
>deleted file mode 100644
>index 85fd97bf6c12..000000000000
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/docs/usage.rst
>+++ /dev/null
>@@ -1,242 +0,0 @@
>-Getting Started
>-===============
>-
>-Installing wptrunner
>---------------------
>-
>-The easiest way to install wptrunner is into a virtualenv, using pip::
>-
>-  virtualenv wptrunner
>-  cd wptrunner
>-  source bin/activate
>-  pip install wptrunner
>-
>-This will install the base dependencies for wptrunner, but not any
>-extra dependencies required to test against specific browsers. In
>-order to do this you must use use the extra requirements files in
>-``$VIRTUAL_ENV/requirements/requirements_browser.txt``. For example,
>-in order to test against Firefox you would have to run::
>-
>-  pip install -r requirements/requirements_firefox.txt
>-
>-If you intend to work on the code, the ``-e`` option to pip should be
>-used in combination with a source checkout i.e. inside a virtual
>-environment created as above::
>-
>-  git clone https://github.com/w3c/wptrunner.git
>-  cd wptrunner
>-  pip install -e ./
>-
>-In addition to the dependencies installed by pip, wptrunner requires
>-a copy of the web-platform-tests repository. This can be located
>-anywhere on the filesystem, but the easiest option is to put it
>-under the same parent directory as the wptrunner checkout::
>-
>-  git clone https://github.com/web-platform-tests/wpt.git
>-
>-It is also necessary to generate a web-platform-tests ``MANIFEST.json``
>-file. It's recommended to also put that under the same parent directory as
>-the wptrunner checkout, in a directory named ``meta``::
>-
>-  mkdir meta
>-  cd web-platform-tests
>-  python manifest --path ../meta/MANIFEST.json
>-
>-The ``MANIFEST.json`` file needs to be regenerated each time the
>-web-platform-tests checkout is updated. To aid with the update process
>-there is a tool called ``wptupdate``, which is described in
>-:ref:`wptupdate-label`.
>-
>-Running the Tests
>------------------
>-
>-A test run is started using the ``wptrunner`` command.  The command
>-takes multiple options, of which the following are most significant:
>-
>-``--product`` (defaults to `firefox`)
>-  The product to test against: `chrome`, `firefox`, or `servo`.
>-
>-``--binary`` (required if product is `firefox` or `servo`)
>-  The path to a binary file for the product (browser) to test against.
>-
>-``--webdriver-binary`` (required if product is `chrome`)
>-  The path to a `*driver` binary; e.g., a `chromedriver` binary.
>-
>-``--certutil-binary`` (required if product is `firefox` [#]_)
>-  The path to a `certutil` binary (for tests that must be run over https).
>-
>-``--metadata`` (required only when not `using default paths`_)
>-  The path to a directory containing test metadata. [#]_
>-
>-``--tests`` (required only when not `using default paths`_)
>-  The path to a directory containing a web-platform-tests checkout.
>-
>-``--prefs-root`` (required only when testing a Firefox binary)
>-  The path to a directory containing Firefox test-harness preferences. [#]_
>-
>-``--config`` (should default to `wptrunner.default.ini`)
>-  The path to the config (ini) file.
>-
>-.. [#] The ``--certutil-binary`` option is required when the product is
>-   ``firefox`` unless ``--ssl-type=none`` is specified.
>-
>-.. [#] The ``--metadata`` path is to a directory that contains:
>-
>-  * a ``MANIFEST.json`` file (the web-platform-tests documentation has
>-    instructions on generating this file)
>-  * (optionally) any expectation files (see :ref:`wptupdate-label`)
>-
>-.. [#] Example ``--prefs-root`` value: ``~/mozilla-central/testing/profiles``.
>-
>-There are also a variety of other command-line options available; use
>-``--help`` to list them.
>-
>-The following examples show how to start wptrunner with various options.
>-
>-------------------
>-Starting wptrunner
>-------------------
>-
>-The examples below assume the following directory layout,
>-though no specific folder structure is required::
>-
>-  ~/testtwf/wptrunner          # wptrunner checkout
>-  ~/testtwf/web-platform-tests # web-platform-tests checkout
>-  ~/testtwf/meta               # metadata
>-
>-To test a Firefox Nightly build in an OS X environment, you might start
>-wptrunner using something similar to the following example::
>-
>-  wptrunner --metadata=~/testtwf/meta/ --tests=~/testtwf/web-platform-tests/ \
>-    --binary=~/mozilla-central/obj-x86_64-apple-darwin14.3.0/dist/Nightly.app/Contents/MacOS/firefox \
>-    --certutil-binary=~/mozilla-central/obj-x86_64-apple-darwin14.3.0/security/nss/cmd/certutil/certutil \
>-    --prefs-root=~/mozilla-central/testing/profiles
>-
>-
>-And to test a Chromium build in an OS X environment, you might start
>-wptrunner using something similar to the following example::
>-
>-  wptrunner --metadata=~/testtwf/meta/ --tests=~/testtwf/web-platform-tests/ \
>-    --binary=~/chromium/src/out/Release/Chromium.app/Contents/MacOS/Chromium \
>-    --webdriver-binary=/usr/local/bin/chromedriver --product=chrome
>-
>---------------------
>-Running test subsets
>---------------------
>-
>-To restrict a test run just to tests in a particular web-platform-tests
>-subdirectory, specify the directory name in the positional arguments after
>-the options; for example, run just the tests in the `dom` subdirectory::
>-
>-  wptrunner --metadata=~/testtwf/meta --tests=~/testtwf/web-platform-tests/ \
>-    --binary=/path/to/firefox --certutil-binary=/path/to/certutil \
>-    --prefs-root=/path/to/testing/profiles \
>-    dom
>-
>--------------------
>-Running in parallel
>--------------------
>-
>-To speed up the testing process, use the ``--processes`` option to have
>-wptrunner run multiple browser instances in parallel. For example, to
>-have wptrunner attempt to run tests against with six browser instances
>-in parallel, specify ``--processes=6``. But note that behaviour in this
>-mode is necessarily less deterministic than with ``--processes=1`` (the
>-default), so there may be more noise in the test results.
>-
>--------------------
>-Using default paths
>--------------------
>-
>-The (otherwise-required) ``--tests`` and ``--metadata`` command-line
>-options/flags be omitted if any configuration file is found that
>-contains a section specifying the ``tests`` and ``metadata`` keys.
>-
>-See the `Configuration File`_ section for more information about
>-configuration files, including information about their expected
>-locations.
>-
>-The content of the ``wptrunner.default.ini`` default configuration file
>-makes wptrunner look for tests (that is, a web-platform-tests checkout)
>-as a subdirectory of the current directory named ``tests``, and for
>-metadata files in a subdirectory of the current directory named ``meta``.
>-
>-Output
>-------
>-
>-wptrunner uses `the mozlog package
>-<https://firefox-source-docs.mozilla.org/mozbase/mozlog.html>`_) for
>-output. This structures events such as test results or log messages as
>-JSON objects that can then be fed to other tools for
>-interpretation. More details about the message format are given in
>-`the mozlog documentation
>-<https://firefox-source-docs.mozilla.org/mozbase/mozlog.html>`_.
>-
>-By default the raw JSON messages are dumped to stdout. This is
>-convenient for piping into other tools, but not ideal for humans
>-reading the output. `mozlog
>-<https://firefox-source-docs.mozilla.org/mozbase/mozlog.html>`_ comes
>-with several other formatters, which are accessible through command
>-line options. The general format of these options is
>-``--log-name=dest``, where ``name`` is the name of the format and
>-``dest`` is a path to a destination file, or ``-`` for stdout. The raw
>-JSON data is written by the ``raw`` formatter so, the default setup
>-corresponds to ``--log-raw=-``.
>-
>-A reasonable output format for humans is provided as ``mach``. So in
>-order to output the full raw log to a file and a human-readable
>-summary to stdout, one might pass the options::
>-
>-  --log-raw=output.log --log-mach=-
>-
>-Configuration File
>-------------------
>-
>-wptrunner uses a ``.ini`` file to control some configuration
>-sections. The file has three sections; ``[products]``,
>-``[manifest:default]`` and ``[web-platform-tests]``.
>-
>-``[products]`` is used to
>-define the set of available products. By default this section is empty
>-which means that all the products distributed with wptrunner are
>-enabled (although their dependencies may not be installed). The set
>-of enabled products can be set by using the product name as the
>-key. For built in products the value is empty. It is also possible to
>-provide the path to a script implementing the browser functionality
>-e.g.::
>-
>-  [products]
>-  chrome =
>-  netscape4 = path/to/netscape.py
>-
>-``[manifest:default]`` specifies the default paths for the tests and metadata,
>-relative to the config file. For example::
>-
>-  [manifest:default]
>-  tests = ~/testtwf/web-platform-tests
>-  metadata = ~/testtwf/meta
>-
>-
>-``[web-platform-tests]`` is used to set the properties of the upstream
>-repository when updating the paths. ``remote_url`` specifies the git
>-url to pull from; ``branch`` the branch to sync against and
>-``sync_path`` the local path, relative to the configuration file, to
>-use when checking out the tests e.g.::
>-
>-  [web-platform-tests]
>-  remote_url = https://github.com/web-platform-tests/wpt.git
>-  branch = master
>-  sync_path = sync
>-
>-A configuration file must contain all the above fields; falling back
>-to the default values for unspecified fields is not yet supported.
>-
>-The ``wptrunner`` and ``wptupdate`` commands will use configuration
>-files in the following order:
>-
>- * Any path supplied with a ``--config`` flag to the command.
>-
>- * A file called ``wptrunner.ini`` in the current directory
>-
>- * The default configuration file (``wptrunner.default.ini`` in the
>-   source directory)
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements.txt
>index 1eba114a31c2..8356c4785dc0 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements.txt
>@@ -1,9 +1,8 @@
> html5lib==1.1
>-mozinfo==1.2.1  # https://bugzilla.mozilla.org/show_bug.cgi?id=1621226
>-mozlog==6.1
>-mozdebug==0.2
>-# Pillow 7 requires Python 3
>-pillow==6.2.2  # pyup: <7.0
>-urllib3[secure]==1.25.10
>-requests==2.24.0
>-six==1.15.0
>+mozinfo==1.2.2  # https://bugzilla.mozilla.org/show_bug.cgi?id=1621226
>+mozlog==7.1.0
>+mozdebug==0.3.0
>+pillow==8.3.1
>+urllib3[secure]==1.26.6
>+requests==2.25.1
>+six==1.16.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_chrome.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_chrome.txt
>index e7e7161b1426..79619558a5dc 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_chrome.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_chrome.txt
>@@ -1 +1 @@
>-mozprocess==1.2.0
>+mozprocess==1.3.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_chrome_android.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_chrome_android.txt
>index e7e7161b1426..79619558a5dc 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_chrome_android.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_chrome_android.txt
>@@ -1 +1 @@
>-mozprocess==1.2.0
>+mozprocess==1.3.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_edge.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_edge.txt
>index 0a61208d77c1..7ad0180b8545 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_edge.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_edge.txt
>@@ -1,2 +1,2 @@
>-mozprocess==1.2.0
>+mozprocess==1.3.0
> selenium==3.141.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_firefox.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_firefox.txt
>index 8b45703a5596..6bf280c47c92 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_firefox.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_firefox.txt
>@@ -1,10 +1,10 @@
> marionette_driver==3.1.0
>-mozcrash==2.0.0
>-mozinstall==2.0.0
>+mozcrash==2.1.0
>+mozinstall==2.0.1
> mozleak==0.2
> moznetwork==1.1.0
>-mozprocess==1.2.0
>+mozprocess==1.3.0
> mozprofile==2.5.0
>-mozrunner==8.0.0
>+mozrunner==8.2.1
> mozversion==2.3.0
>-psutil==5.7.2
>+psutil==5.8.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_ie.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_ie.txt
>index 0a61208d77c1..7ad0180b8545 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_ie.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_ie.txt
>@@ -1,2 +1,2 @@
>-mozprocess==1.2.0
>+mozprocess==1.3.0
> selenium==3.141.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_opera.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_opera.txt
>index 0a61208d77c1..7ad0180b8545 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_opera.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_opera.txt
>@@ -1,2 +1,2 @@
>-mozprocess==1.2.0
>+mozprocess==1.3.0
> selenium==3.141.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_safari.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_safari.txt
>index e7e7161b1426..65b76aa85cc4 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_safari.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_safari.txt
>@@ -1 +1,2 @@
>-mozprocess==1.2.0
>+mozprocess==1.3.0
>+psutil==5.8.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_sauce.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_sauce.txt
>index 34c66ee238b6..d1d0f7e2bee2 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_sauce.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_sauce.txt
>@@ -1,3 +1,3 @@
>-mozprocess==1.2.0
>+mozprocess==1.3.0
> selenium==3.141.0
>-requests==2.24.0
>+requests==2.25.1
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_servo.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_servo.txt
>index e7e7161b1426..79619558a5dc 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_servo.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_servo.txt
>@@ -1 +1 @@
>-mozprocess==1.2.0
>+mozprocess==1.3.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_webkit.txt b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_webkit.txt
>index e7e7161b1426..79619558a5dc 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/requirements_webkit.txt
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/requirements_webkit.txt
>@@ -1 +1 @@
>-mozprocess==1.2.0
>+mozprocess==1.3.0
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/setup.py b/WebDriverTests/imported/w3c/tools/wptrunner/setup.py
>index a459e2c47141..c20955848dbf 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/setup.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/setup.py
>@@ -2,8 +2,6 @@
> # License, v. 2.0. If a copy of the MPL was not distributed with this file,
> # You can obtain one at http://mozilla.org/MPL/2.0/.
> 
>-from __future__ import print_function
>-
> import glob
> import os
> import sys
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/tox.ini b/WebDriverTests/imported/w3c/tools/wptrunner/tox.ini
>index 798f64a3e422..c49e759ead8c 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/tox.ini
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/tox.ini
>@@ -2,16 +2,12 @@
> xfail_strict=true
> 
> [tox]
>-envlist = py27-{base,chrome,edge,firefox,ie,opera,safari,sauce,servo,webkit,webkitgtk_minibrowser,epiphany},{py35,py36,py37,py38}-base
>+envlist = py39-{base,chrome,edge,firefox,ie,opera,safari,sauce,servo,webkit,webkitgtk_minibrowser,epiphany},{py36,py37,py38}-base
> skip_missing_interpreters = False
> 
> [testenv]
> deps =
>-     pytest>=2.9
>-     pytest-cov
>-     pytest-xdist
>-     # mock no longer supports Python 2 since v4
>-     mock==3.*
>+     -r{toxinidir}/../requirements_pytest.txt
>      -r{toxinidir}/requirements.txt
>      chrome: -r{toxinidir}/requirements_chrome.txt
>      edge: -r{toxinidir}/requirements_edge.txt
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/android_weblayer.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/android_weblayer.py
>index 6110450b7282..4bd871d1fbd5 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/android_weblayer.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/android_weblayer.py
>@@ -1,9 +1,8 @@
>-import subprocess
>-
>-from .base import Browser, ExecutorBrowser, require_arg
>-from .base import get_timeout_multiplier   # noqa: F401
>+from .base import NullBrowser  # noqa: F401
>+from .base import require_arg
>+from .base import get_timeout_multiplier  # noqa: F401
> from .chrome import executor_kwargs as chrome_executor_kwargs
>-from ..webdriver_server import ChromeDriverServer
>+from .chrome_android import ChromeAndroidBrowserBase
> from ..executors.executorwebdriver import (WebDriverTestharnessExecutor,  # noqa: F401
>                                            WebDriverRefTestExecutor)  # noqa: F401
> from ..executors.executorchrome import ChromeDriverWdspecExecutor  # noqa: F401
>@@ -11,7 +10,8 @@ from ..executors.executorchrome import ChromeDriverWdspecExecutor  # noqa: F401
> 
> __wptrunner__ = {"product": "android_weblayer",
>                  "check_args": "check_args",
>-                 "browser": "WeblayerShell",
>+                 "browser": {None: "WeblayerShell",
>+                             "wdspec": "NullBrowser"},
>                  "executor": {"testharness": "WebDriverTestharnessExecutor",
>                               "reftest": "WebDriverRefTestExecutor",
>                               "wdspec": "ChromeDriverWdspecExecutor"},
>@@ -28,23 +28,24 @@ def check_args(**kwargs):
>     require_arg(kwargs, "webdriver_binary")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {"binary": kwargs["binary"],
>             "device_serial": kwargs["device_serial"],
>             "webdriver_binary": kwargs["webdriver_binary"],
>-            "webdriver_args": kwargs.get("webdriver_args")}
>+            "webdriver_args": kwargs.get("webdriver_args"),
>+            "stackwalk_binary": kwargs.get("stackwalk_binary"),
>+            "symbols_path": kwargs.get("symbols_path")}
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>     # Use update() to modify the global list in place.
>     _wptserve_ports.update(set(
>-        server_config['ports']['http'] + server_config['ports']['https'] +
>-        server_config['ports']['ws'] + server_config['ports']['wss']
>+        test_environment.config['ports']['http'] + test_environment.config['ports']['https'] +
>+        test_environment.config['ports']['ws'] + test_environment.config['ports']['wss']
>     ))
> 
>-    executor_kwargs = chrome_executor_kwargs(test_type, server_config,
>-                                             cache_manager, run_info_data,
>+    executor_kwargs = chrome_executor_kwargs(logger, test_type, test_environment, run_info_data,
>                                              **kwargs)
>     del executor_kwargs["capabilities"]["goog:chromeOptions"]["prefs"]
>     capabilities = executor_kwargs["capabilities"]
>@@ -74,61 +75,22 @@ def env_options():
>     return {"server_host": "127.0.0.1"}
> 
> 
>-#TODO: refactor common elements of WeblayerShell and ChromeAndroidBrowser
>-class WeblayerShell(Browser):
>+class WeblayerShell(ChromeAndroidBrowserBase):
>     """Chrome is backed by chromedriver, which is supplied through
>     ``wptrunner.webdriver.ChromeDriverServer``.
>     """
> 
>-    def __init__(self, logger, binary, webdriver_binary="chromedriver",
>+    def __init__(self, logger, binary,
>+                 webdriver_binary="chromedriver",
>+                 remote_queue=None,
>                  device_serial=None,
>-                 webdriver_args=None):
>+                 webdriver_args=None,
>+                 stackwalk_binary=None,
>+                 symbols_path=None):
>         """Creates a new representation of Chrome.  The `binary` argument gives
>         the browser binary to use for testing."""
>-        Browser.__init__(self, logger)
>+        super(WeblayerShell, self).__init__(logger,
>+                webdriver_binary, remote_queue, device_serial,
>+                webdriver_args, stackwalk_binary, symbols_path)
>         self.binary = binary
>-        self.device_serial = device_serial
>-        self.server = ChromeDriverServer(self.logger,
>-                                         binary=webdriver_binary,
>-                                         args=webdriver_args)
>-        self.setup_adb_reverse()
>-
>-    def _adb_run(self, args):
>-        cmd = ['adb']
>-        if self.device_serial:
>-            cmd.extend(['-s', self.device_serial])
>-        cmd.extend(args)
>-        self.logger.info(' '.join(cmd))
>-        subprocess.check_call(cmd)
>-
>-    def setup_adb_reverse(self):
>-        self._adb_run(['wait-for-device'])
>-        self._adb_run(['forward', '--remove-all'])
>-        self._adb_run(['reverse', '--remove-all'])
>-        # "adb reverse" basically forwards network connection from device to
>-        # host.
>-        for port in _wptserve_ports:
>-            self._adb_run(['reverse', 'tcp:%d' % port, 'tcp:%d' % port])
>-
>-    def start(self, **kwargs):
>-        self.server.start(block=False)
>-
>-    def stop(self, force=False):
>-        self.server.stop(force=force)
>-
>-    def pid(self):
>-        return self.server.pid
>-
>-    def is_alive(self):
>-        # TODO(ato): This only indicates the driver is alive,
>-        # and doesn't say anything about whether a browser session
>-        # is active.
>-        return self.server.is_alive()
>-
>-    def cleanup(self):
>-        self.stop()
>-        self._adb_run(['forward', '--remove-all'])
>-        self._adb_run(['reverse', '--remove-all'])
>-
>-    def executor_browser(self):
>-        return ExecutorBrowser, {"webdriver_url": self.server.url}
>+        self.wptserver_ports = _wptserve_ports
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/base.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/base.py
>index 99f6e5cff4c8..282e2d7ad5ee 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/base.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/base.py
>@@ -1,34 +1,14 @@
>+import enum
> import os
> import platform
> import socket
> from abc import ABCMeta, abstractmethod
>-from copy import deepcopy
>-from six import iteritems
> 
> from ..wptcommandline import require_arg  # noqa: F401
> 
> here = os.path.dirname(__file__)
> 
> 
>-def inherit(super_module, child_globals, product_name):
>-    super_wptrunner = super_module.__wptrunner__
>-    child_globals["__wptrunner__"] = child_wptrunner = deepcopy(super_wptrunner)
>-
>-    child_wptrunner["product"] = product_name
>-
>-    for k in ("check_args", "browser", "browser_kwargs", "executor_kwargs",
>-              "env_extras", "env_options", "timeout_multiplier"):
>-        attr = super_wptrunner[k]
>-        child_globals[attr] = getattr(super_module, attr)
>-
>-    for v in super_module.__wptrunner__["executor"].values():
>-        child_globals[v] = getattr(super_module, v)
>-
>-    if "run_info_extras" in super_wptrunner:
>-        attr = super_wptrunner["run_info_extras"]
>-        child_globals[attr] = getattr(super_module, attr)
>-
>-
> def cmd_arg(name, value=None):
>     prefix = "-" if platform.system() == "Windows" else "--"
>     rv = prefix + name
>@@ -65,7 +45,7 @@ def get_free_port():
>         s = socket.socket()
>         try:
>             s.bind(("127.0.0.1", 0))
>-        except socket.error:
>+        except OSError:
>             continue
>         else:
>             return s.getsockname()[1]
>@@ -126,6 +106,12 @@ class Browser(object):
>         pass
> 
>     def settings(self, test):
>+        """Dictionary of metadata that is constant for a specific launch of a browser.
>+
>+        This is used to determine when the browser instance configuration changes, requiring
>+        a relaunch of the browser. The test runner calls this method for each test, and if the
>+        returned value differs from that for the previous test, the browser is relaunched.
>+        """
>         return {}
> 
>     @abstractmethod
>@@ -157,6 +143,10 @@ class Browser(object):
>         with which it should be instantiated"""
>         return ExecutorBrowser, {}
> 
>+    def maybe_parse_tombstone(self):
>+        """Possibly parse tombstones on Android device for Android target"""
>+        pass
>+
>     def check_crash(self, process, test):
>         """Check if a crash occured and output any useful information to the
>         log. Returns a boolean indicating whether a crash occured."""
>@@ -182,11 +172,8 @@ class NullBrowser(Browser):
>     def is_alive(self):
>         return True
> 
>-    def on_output(self, line):
>-        raise NotImplementedError
> 
>-
>-class ExecutorBrowser(object):
>+class ExecutorBrowser:
>     """View of the Browser used by the Executor object.
>     This is needed because the Executor runs in a child process and
>     we can't ship Browser instances between processes on Windows.
>@@ -196,5 +183,95 @@ class ExecutorBrowser(object):
>     up the browser from the runner process.
>     """
>     def __init__(self, **kwargs):
>-        for k, v in iteritems(kwargs):
>+        for k, v in kwargs.items():
>             setattr(self, k, v)
>+
>+
>+@enum.unique
>+class OutputHandlerState(enum.IntEnum):
>+    BEFORE_PROCESS_START = 1
>+    AFTER_PROCESS_START = 2
>+    AFTER_HANDLER_START = 3
>+    AFTER_PROCESS_STOP = 4
>+
>+
>+class OutputHandler:
>+    """Class for handling output from a browser process.
>+
>+    This class is responsible for consuming the logging from a browser process
>+    and passing it into the relevant logger. A class instance is designed to
>+    be passed as the processOutputLine argument to mozprocess.ProcessHandler.
>+
>+    The setup of this class is complex for various reasons:
>+
>+    * We need to create an instance of the class before starting the process
>+    * We want access to data about the running process e.g. the pid
>+    * We want to launch the process and later setup additional log handling
>+      which is restrospectively applied to any existing output (this supports
>+      prelaunching browsers for performance, but having log output depend on the
>+      tests that are run e.g. for leak suppression).
>+
>+    Therefore the lifecycle is as follows::
>+
>+      output_handler = OutputHandler(logger, command, **output_handler_kwargs)
>+      proc = ProcessHandler(command, ..., processOutputLine=output_handler)
>+      output_handler.after_process_start(proc.pid)
>+      [...]
>+      # All logging to this point was buffered in-memory, but after start()
>+      # it's actually sent to the logger.
>+      output_handler.start(**output_logger_start_kwargs)
>+      [...]
>+      proc.wait()
>+      output_handler.after_process_stop()
>+
>+    Since the process lifetime and the output handler lifetime are coupled (it doesn't
>+    work to reuse an output handler for multiple processes), it might make sense to have
>+    a single class that owns the process and the output processing for the process.
>+    This is complicated by the fact that we don't always run the process directly,
>+    but sometimes use a wrapper e.g. mozrunner.
>+    """
>+
>+    def __init__(self, logger, command, **kwargs):
>+        self.logger = logger
>+        self.command = command
>+        self.pid = None
>+        self.state = OutputHandlerState.BEFORE_PROCESS_START
>+        self.line_buffer = []
>+
>+    def after_process_start(self, pid):
>+        assert self.state == OutputHandlerState.BEFORE_PROCESS_START
>+        self.logger.debug("OutputHandler.after_process_start")
>+        self.pid = pid
>+        self.state = OutputHandlerState.AFTER_PROCESS_START
>+
>+    def start(self, **kwargs):
>+        assert self.state == OutputHandlerState.AFTER_PROCESS_START
>+        self.logger.debug("OutputHandler.start")
>+        # Need to change the state here before we try to empty the buffer
>+        # or we'll just re-buffer the existing output.
>+        self.state = OutputHandlerState.AFTER_HANDLER_START
>+        for item in self.line_buffer:
>+            self(item)
>+        self.line_buffer = None
>+
>+    def after_process_stop(self, clean_shutdown=True):
>+        # If we didn't get as far as configure, just
>+        # dump all logs with no configuration
>+        self.logger.debug("OutputHandler.after_process_stop")
>+        if self.state < OutputHandlerState.AFTER_HANDLER_START:
>+            self.start()
>+        self.state = OutputHandlerState.AFTER_PROCESS_STOP
>+
>+    def __call__(self, line):
>+        if self.state < OutputHandlerState.AFTER_HANDLER_START:
>+            self.line_buffer.append(line)
>+            return
>+
>+        # Could assert that there's no output handled once we're in the
>+        # after_process_stop phase, although technically there's a race condition
>+        # here because we don't know the logging thread has finished draining the
>+        # logs. The solution might be to move this into mozprocess itself.
>+
>+        self.logger.process_output(self.pid,
>+                                   line.decode("utf8", "replace"),
>+                                   command=" ".join(self.command) if self.command else "")
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/chrome.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/chrome.py
>index fd251a431c30..0b6a0c618dfc 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/chrome.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/chrome.py
>@@ -1,5 +1,6 @@
> from . import chrome_spki_certs
> from .base import Browser, ExecutorBrowser, require_arg
>+from .base import NullBrowser  # noqa: F401
> from .base import get_timeout_multiplier   # noqa: F401
> from ..webdriver_server import ChromeDriverServer
> from ..executors import executor_kwargs as base_executor_kwargs
>@@ -12,7 +13,8 @@ from ..executors.executorchrome import (ChromeDriverWdspecExecutor,  # noqa: F40
> 
> __wptrunner__ = {"product": "chrome",
>                  "check_args": "check_args",
>-                 "browser": "ChromeBrowser",
>+                 "browser": {None: "ChromeBrowser",
>+                             "wdspec": "NullBrowser"},
>                  "executor": {"testharness": "WebDriverTestharnessExecutor",
>                               "reftest": "WebDriverRefTestExecutor",
>                               "print-reftest": "ChromeDriverPrintRefTestExecutor",
>@@ -28,16 +30,15 @@ def check_args(**kwargs):
>     require_arg(kwargs, "webdriver_binary")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {"binary": kwargs["binary"],
>             "webdriver_binary": kwargs["webdriver_binary"],
>             "webdriver_args": kwargs.get("webdriver_args")}
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>-    executor_kwargs = base_executor_kwargs(test_type, server_config,
>-                                           cache_manager, run_info_data,
>+    executor_kwargs = base_executor_kwargs(test_type, test_environment, run_info_data,
>                                            **kwargs)
>     executor_kwargs["close_after_done"] = True
>     executor_kwargs["supports_eager_pageload"] = False
>@@ -81,9 +82,31 @@ def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>     # Point all .test domains to localhost for Chrome
>     chrome_options["args"].append("--host-resolver-rules=MAP nonexistent.*.test ~NOTFOUND, MAP *.test 127.0.0.1")
> 
>+    # Classify `http-private`, `http-public` and https variants in the
>+    # appropriate IP address spaces.
>+    # For more details, see: https://github.com/web-platform-tests/rfcs/blob/master/rfcs/address_space_overrides.md
>+    address_space_overrides_ports = [
>+        ("http-private", "private"),
>+        ("http-public", "public"),
>+        ("https-private", "private"),
>+        ("https-public", "public"),
>+    ]
>+    address_space_overrides_arg = ",".join(
>+        "127.0.0.1:{}={}".format(port_number, address_space)
>+        for port_name, address_space in address_space_overrides_ports
>+        for port_number in test_environment.config.ports.get(port_name, [])
>+    )
>+    if address_space_overrides_arg:
>+        chrome_options["args"].append(
>+            "--ip-address-space-overrides=" + address_space_overrides_arg)
>+
>     if kwargs["enable_mojojs"]:
>         chrome_options["args"].append("--enable-blink-features=MojoJS,MojoJSTest")
> 
>+    if kwargs["enable_swiftshader"]:
>+        # https://chromium.googlesource.com/chromium/src/+/HEAD/docs/gpu/swiftshader.md
>+        chrome_options["args"].extend(["--use-gl=angle", "--use-angle=swiftshader"])
>+
>     # Copy over any other flags that were passed in via --binary_args
>     if kwargs["binary_args"] is not None:
>         chrome_options["args"].extend(kwargs["binary_args"])
>@@ -113,7 +136,7 @@ class ChromeBrowser(Browser):
>     """
> 
>     def __init__(self, logger, binary, webdriver_binary="chromedriver",
>-                 webdriver_args=None):
>+                 webdriver_args=None, **kwargs):
>         """Creates a new representation of Chrome.  The `binary` argument gives
>         the browser binary to use for testing."""
>         Browser.__init__(self, logger)
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/chrome_android.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/chrome_android.py
>index 485b96f31e7d..3ba01588b294 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/chrome_android.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/chrome_android.py
>@@ -1,7 +1,9 @@
>+import mozprocess
> import subprocess
> 
> from .base import Browser, ExecutorBrowser, require_arg
> from .base import get_timeout_multiplier   # noqa: F401
>+from .base import NullBrowser  # noqa: F401
> from .chrome import executor_kwargs as chrome_executor_kwargs
> from ..webdriver_server import ChromeDriverServer
> from ..executors.executorwebdriver import (WebDriverTestharnessExecutor,  # noqa: F401
>@@ -11,7 +13,8 @@ from ..executors.executorchrome import ChromeDriverWdspecExecutor  # noqa: F401
> 
> __wptrunner__ = {"product": "chrome_android",
>                  "check_args": "check_args",
>-                 "browser": "ChromeAndroidBrowser",
>+                 "browser": {None: "ChromeAndroidBrowser",
>+                             "wdspec": "NullBrowser"},
>                  "executor": {"testharness": "WebDriverTestharnessExecutor",
>                               "reftest": "WebDriverRefTestExecutor",
>                               "wdspec": "ChromeDriverWdspecExecutor"},
>@@ -29,23 +32,24 @@ def check_args(**kwargs):
>     require_arg(kwargs, "webdriver_binary")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {"package_name": kwargs["package_name"],
>             "device_serial": kwargs["device_serial"],
>             "webdriver_binary": kwargs["webdriver_binary"],
>-            "webdriver_args": kwargs.get("webdriver_args")}
>+            "webdriver_args": kwargs.get("webdriver_args"),
>+            "stackwalk_binary": kwargs.get("stackwalk_binary"),
>+            "symbols_path": kwargs.get("symbols_path")}
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>     # Use update() to modify the global list in place.
>     _wptserve_ports.update(set(
>-        server_config['ports']['http'] + server_config['ports']['https'] +
>-        server_config['ports']['ws'] + server_config['ports']['wss']
>+        test_environment.config['ports']['http'] + test_environment.config['ports']['https'] +
>+        test_environment.config['ports']['ws'] + test_environment.config['ports']['wss']
>     ))
> 
>-    executor_kwargs = chrome_executor_kwargs(test_type, server_config,
>-                                             cache_manager, run_info_data,
>+    executor_kwargs = chrome_executor_kwargs(logger, test_type, test_environment, run_info_data,
>                                              **kwargs)
>     # Remove unsupported options on mobile.
>     del executor_kwargs["capabilities"]["goog:chromeOptions"]["prefs"]
>@@ -69,20 +73,82 @@ def env_options():
>     return {"server_host": "127.0.0.1"}
> 
> 
>-class ChromeAndroidBrowser(Browser):
>-    """Chrome is backed by chromedriver, which is supplied through
>-    ``wptrunner.webdriver.ChromeDriverServer``.
>-    """
>+class LogcatRunner(object):
>+    def __init__(self, logger, browser, remote_queue):
>+        self.logger = logger
>+        self.browser = browser
>+        self.remote_queue = remote_queue
>+
>+    def start(self):
>+        try:
>+            self._run()
>+        except KeyboardInterrupt:
>+            self.stop()
>+
>+    def _run(self):
>+        try:
>+            # TODO: adb logcat -c fail randomly with message
>+            # "failed to clear the 'main' log"
>+            self.browser.clear_log()
>+        except subprocess.CalledProcessError:
>+            self.logger.error("Failed to clear logcat buffer")
>+
>+        self._cmd = self.browser.logcat_cmd()
>+        self._proc = mozprocess.ProcessHandler(
>+            self._cmd,
>+            processOutputLine=self.on_output,
>+            storeOutput=False)
>+        self._proc.run()
>+
>+    def _send_message(self, command, *args):
>+        try:
>+            self.remote_queue.put((command, args))
>+        except AssertionError:
>+            self.logger.warning("Error when send to remote queue")
> 
>-    def __init__(self, logger, package_name, webdriver_binary="chromedriver",
>-                 device_serial=None, webdriver_args=None):
>-        Browser.__init__(self, logger)
>-        self.package_name = package_name
>+    def stop(self, force=False):
>+        if self.is_alive():
>+            kill_result = self._proc.kill()
>+            if force and kill_result != 0:
>+                self._proc.kill(9)
>+
>+    def is_alive(self):
>+        return hasattr(self._proc, "proc") and self._proc.poll() is None
>+
>+    def on_output(self, line):
>+        data = {
>+            "action": "process_output",
>+            "process": "LOGCAT",
>+            "command": "logcat",
>+            "data": line
>+        }
>+        self._send_message("log", data)
>+
>+
>+class ChromeAndroidBrowserBase(Browser):
>+    def __init__(self, logger,
>+                 webdriver_binary="chromedriver",
>+                 remote_queue = None,
>+                 device_serial=None,
>+                 webdriver_args=None,
>+                 stackwalk_binary=None,
>+                 symbols_path=None):
>+        super(ChromeAndroidBrowserBase, self).__init__(logger)
>         self.device_serial = device_serial
>+        self.stackwalk_binary = stackwalk_binary
>+        self.symbols_path = symbols_path
>+        self.remote_queue = remote_queue
>         self.server = ChromeDriverServer(self.logger,
>                                          binary=webdriver_binary,
>                                          args=webdriver_args)
>+        if self.remote_queue is not None:
>+            self.logcat_runner = LogcatRunner(self.logger,
>+                                          self, self.remote_queue)
>+
>+    def setup(self):
>         self.setup_adb_reverse()
>+        if self.remote_queue is not None:
>+            self.logcat_runner.start()
> 
>     def _adb_run(self, args):
>         cmd = ['adb']
>@@ -92,14 +158,6 @@ class ChromeAndroidBrowser(Browser):
>         self.logger.info(' '.join(cmd))
>         subprocess.check_call(cmd)
> 
>-    def setup_adb_reverse(self):
>-        self._adb_run(['wait-for-device'])
>-        self._adb_run(['forward', '--remove-all'])
>-        self._adb_run(['reverse', '--remove-all'])
>-        # "adb reverse" forwards network connection from device to host.
>-        for port in _wptserve_ports:
>-            self._adb_run(['reverse', 'tcp:%d' % port, 'tcp:%d' % port])
>-
>     def start(self, **kwargs):
>         self.server.start(block=False)
> 
>@@ -119,6 +177,60 @@ class ChromeAndroidBrowser(Browser):
>         self.stop()
>         self._adb_run(['forward', '--remove-all'])
>         self._adb_run(['reverse', '--remove-all'])
>+        if self.remote_queue is not None:
>+            self.logcat_runner.stop(force=True)
> 
>     def executor_browser(self):
>         return ExecutorBrowser, {"webdriver_url": self.server.url}
>+
>+    def clear_log(self):
>+        self._adb_run(['logcat', '-c'])
>+
>+    def logcat_cmd(self):
>+        cmd = ['adb']
>+        if self.device_serial:
>+            cmd.extend(['-s', self.device_serial])
>+        cmd.extend(['logcat', '*:D'])
>+        return cmd
>+
>+    def check_crash(self, process, test):
>+        self.maybe_parse_tombstone()
>+        # Existence of a tombstone does not necessarily mean test target has
>+        # crashed. Always return False so we don't change the test results.
>+        return False
>+
>+    def maybe_parse_tombstone(self):
>+        if self.stackwalk_binary:
>+            cmd = [self.stackwalk_binary, "-a", "-w"]
>+            if self.device_serial:
>+                cmd.extend(["--device", self.device_serial])
>+            cmd.extend(["--output-directory", self.symbols_path])
>+            raw_output = subprocess.check_output(cmd)
>+            for line in raw_output.splitlines():
>+                self.logger.process_output("TRACE", line, "logcat")
>+
>+    def setup_adb_reverse(self):
>+        self._adb_run(['wait-for-device'])
>+        self._adb_run(['forward', '--remove-all'])
>+        self._adb_run(['reverse', '--remove-all'])
>+        # "adb reverse" forwards network connection from device to host.
>+        for port in self.wptserver_ports:
>+            self._adb_run(['reverse', 'tcp:%d' % port, 'tcp:%d' % port])
>+
>+class ChromeAndroidBrowser(ChromeAndroidBrowserBase):
>+    """Chrome is backed by chromedriver, which is supplied through
>+    ``wptrunner.webdriver.ChromeDriverServer``.
>+    """
>+
>+    def __init__(self, logger, package_name,
>+                 webdriver_binary="chromedriver",
>+                 remote_queue = None,
>+                 device_serial=None,
>+                 webdriver_args=None,
>+                 stackwalk_binary=None,
>+                 symbols_path=None):
>+        super(ChromeAndroidBrowser, self).__init__(logger,
>+                webdriver_binary, remote_queue, device_serial,
>+                webdriver_args, stackwalk_binary, symbols_path)
>+        self.package_name = package_name
>+        self.wptserver_ports = _wptserve_ports
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/edge.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/edge.py
>index bdb37b3f84c2..3101e9c7bea3 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/edge.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/edge.py
>@@ -1,7 +1,7 @@
>-from __future__ import print_function
> import time
> import subprocess
> from .base import Browser, ExecutorBrowser, require_arg
>+from .base import NullBrowser  # noqa: F401
> from ..webdriver_server import EdgeDriverServer
> from ..executors import executor_kwargs as base_executor_kwargs
> from ..executors.executorselenium import (SeleniumTestharnessExecutor,  # noqa: F401
>@@ -10,7 +10,8 @@ from ..executors.executoredge import EdgeDriverWdspecExecutor  # noqa: F401
> 
> __wptrunner__ = {"product": "edge",
>                  "check_args": "check_args",
>-                 "browser": "EdgeBrowser",
>+                 "browser": {None: "EdgeBrowser",
>+                             "wdspec": "NullBrowser"},
>                  "executor": {"testharness": "SeleniumTestharnessExecutor",
>                               "reftest": "SeleniumRefTestExecutor",
>                               "wdspec": "EdgeDriverWdspecExecutor"},
>@@ -34,7 +35,7 @@ def check_args(**kwargs):
>     require_arg(kwargs, "webdriver_binary")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {"webdriver_binary": kwargs["webdriver_binary"],
>             "webdriver_args": kwargs.get("webdriver_args"),
>             "timeout_multiplier": get_timeout_multiplier(test_type,
>@@ -42,10 +43,9 @@ def browser_kwargs(test_type, run_info_data, config, **kwargs):
>                                                          **kwargs)}
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>-    executor_kwargs = base_executor_kwargs(test_type, server_config,
>-                                           cache_manager, run_info_data, **kwargs)
>+    executor_kwargs = base_executor_kwargs(test_type, test_environment, run_info_data, **kwargs)
>     executor_kwargs["close_after_done"] = True
>     executor_kwargs["timeout_multiplier"] = get_timeout_multiplier(test_type,
>                                                                    run_info_data,
>@@ -65,10 +65,10 @@ def env_options():
> 
> 
> class EdgeBrowser(Browser):
>-    used_ports = set()
>     init_timeout = 60
> 
>-    def __init__(self, logger, webdriver_binary, timeout_multiplier=None, webdriver_args=None):
>+    def __init__(self, logger, webdriver_binary,
>+            timeout_multiplier=None, webdriver_args=None, **kwargs):
>         Browser.__init__(self, logger)
>         self.server = EdgeDriverServer(self.logger,
>                                        binary=webdriver_binary,
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/edge_webdriver.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/edge_webdriver.py
>index c2545de46f0b..e5949fe3e57f 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/edge_webdriver.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/edge_webdriver.py
>@@ -1,12 +1,28 @@
>-from .base import inherit
>-from . import edge
>+from .base import NullBrowser  # noqa: F401
>+from .edge import (EdgeBrowser,  # noqa: F401
>+                   EdgeDriverWdspecExecutor,  # noqa: F401
>+                   check_args,  # noqa: F401
>+                   browser_kwargs,  # noqa: F401
>+                   executor_kwargs,  # noqa: F401
>+                   env_extras,  # noqa: F401
>+                   env_options,  # noqa: F401
>+                   run_info_extras,  # noqa: F401
>+                   get_timeout_multiplier)  # noqa: F401
> 
> from ..executors.executorwebdriver import (WebDriverTestharnessExecutor,  # noqa: F401
>                                            WebDriverRefTestExecutor)  # noqa: F401
> 
> 
>-inherit(edge, globals(), "edge_webdriver")
>-
>-# __wptrunner__ magically appears from inherit, F821 is undefined name
>-__wptrunner__["executor"]["testharness"] = "WebDriverTestharnessExecutor"  # noqa: F821
>-__wptrunner__["executor"]["reftest"] = "WebDriverRefTestExecutor"  # noqa: F821
>+__wptrunner__ = {"product": "edge_webdriver",
>+                 "check_args": "check_args",
>+                 "browser": {None: "EdgeBrowser",
>+                             "wdspec": "NullBrowser"},
>+                 "executor": {"testharness": "WebDriverTestharnessExecutor",
>+                              "reftest": "WebDriverRefTestExecutor",
>+                              "wdspec": "EdgeDriverWdspecExecutor"},
>+                 "browser_kwargs": "browser_kwargs",
>+                 "executor_kwargs": "executor_kwargs",
>+                 "env_extras": "env_extras",
>+                 "env_options": "env_options",
>+                 "run_info_extras": "run_info_extras",
>+                 "timeout_multiplier": "get_timeout_multiplier"}
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/firefox.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/firefox.py
>index 151530897d9b..ac27453127ab 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/firefox.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/firefox.py
>@@ -1,9 +1,12 @@
>+import base64
>+import io
> import json
> import os
> import platform
> import signal
> import subprocess
>-import sys
>+import tempfile
>+import zipfile
> from abc import ABCMeta, abstractmethod
> 
> import mozinfo
>@@ -15,26 +18,30 @@ from mozrunner import FirefoxRunner
> from mozrunner.utils import test_environment, get_stack_fixer_function
> from mozcrash import mozcrash
> 
>-from .base import (get_free_port,
>-                   Browser,
>+from .base import (Browser,
>                    ExecutorBrowser,
>-                   require_arg,
>+                   NullBrowser,
>+                   OutputHandler,
>+                   OutputHandlerState,
>+                   browser_command,
>                    cmd_arg,
>-                   browser_command)
>+                   get_free_port,
>+                   require_arg)
> from ..executors import executor_kwargs as base_executor_kwargs
> from ..executors.executormarionette import (MarionetteTestharnessExecutor,  # noqa: F401
>                                             MarionetteRefTestExecutor,  # noqa: F401
>                                             MarionettePrintRefTestExecutor,  # noqa: F401
>                                             MarionetteWdspecExecutor,  # noqa: F401
>                                             MarionetteCrashtestExecutor)  # noqa: F401
>-from ..process import cast_env
>+from ..webdriver_server import WebDriverServer
> 
> 
> here = os.path.dirname(__file__)
> 
> __wptrunner__ = {"product": "firefox",
>                  "check_args": "check_args",
>-                 "browser": "FirefoxBrowser",
>+                 "browser": {None: "FirefoxBrowser",
>+                             "wdspec": "FirefoxWdSpecBrowser"},
>                  "executor": {"crashtest": "MarionetteCrashtestExecutor",
>                               "testharness": "MarionetteTestharnessExecutor",
>                               "reftest": "MarionetteRefTestExecutor",
>@@ -53,11 +60,11 @@ def get_timeout_multiplier(test_type, run_info_data, **kwargs):
>     if kwargs["timeout_multiplier"] is not None:
>         return kwargs["timeout_multiplier"]
>     if test_type == "reftest":
>-        if run_info_data["debug"] or run_info_data.get("asan"):
>+        if run_info_data["debug"] or run_info_data.get("asan") or run_info_data.get("tsan"):
>             return 4
>         else:
>             return 2
>-    elif run_info_data["debug"] or run_info_data.get("asan"):
>+    elif run_info_data["debug"] or run_info_data.get("asan") or run_info_data.get("tsan"):
>         if run_info_data.get("ccov"):
>             return 4
>         else:
>@@ -76,7 +83,7 @@ def check_args(**kwargs):
>     require_arg(kwargs, "binary")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {"binary": kwargs["binary"],
>             "prefs_root": kwargs["prefs_root"],
>             "extra_prefs": kwargs["extra_prefs"],
>@@ -101,13 +108,24 @@ def browser_kwargs(test_type, run_info_data, config, **kwargs):
>             "config": config,
>             "browser_channel": kwargs["browser_channel"],
>             "headless": kwargs["headless"],
>-            "preload_browser": kwargs["preload_browser"]}
>+            "preload_browser": kwargs["preload_browser"] and not kwargs["pause_after_test"] and not kwargs["num_test_groups"] == 1,
>+            "specialpowers_path": kwargs["specialpowers_path"]}
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+class WdSpecProfile(object):
>+    def __init__(self, profile):
>+        self.profile = profile
>+
>+    def __enter__(self):
>+        return self
>+
>+    def __exit__(self, *args, **kwargs):
>+        self.profile.cleanup()
>+
>+
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>-    executor_kwargs = base_executor_kwargs(test_type, server_config,
>-                                           cache_manager, run_info_data,
>+    executor_kwargs = base_executor_kwargs(test_type, test_environment, run_info_data,
>                                            **kwargs)
>     executor_kwargs["close_after_done"] = test_type != "reftest"
>     executor_kwargs["timeout_multiplier"] = get_timeout_multiplier(test_type,
>@@ -121,22 +139,63 @@ def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>         executor_kwargs["reftest_internal"] = kwargs["reftest_internal"]
>         executor_kwargs["reftest_screenshot"] = kwargs["reftest_screenshot"]
>     if test_type == "wdspec":
>-        options = {}
>+        options = {"args": []}
>         if kwargs["binary"]:
>             options["binary"] = kwargs["binary"]
>         if kwargs["binary_args"]:
>             options["args"] = kwargs["binary_args"]
>-        if kwargs["headless"]:
>-            if "args" not in options:
>-                options["args"] = []
>-            if "--headless" not in options["args"]:
>-                options["args"].append("--headless")
>-        options["prefs"] = {
>-            "network.dns.localDomains": ",".join(server_config.domains_set)
>-        }
>-        for pref, value in kwargs["extra_prefs"]:
>-            options["prefs"].update({pref: Preferences.cast(value)})
>+
>+        profile_creator = ProfileCreator(logger,
>+                                         kwargs["prefs_root"],
>+                                         test_environment.config,
>+                                         test_type,
>+                                         kwargs["extra_prefs"],
>+                                         kwargs["gecko_e10s"],
>+                                         kwargs["enable_fission"],
>+                                         kwargs["browser_channel"],
>+                                         kwargs["binary"],
>+                                         kwargs["certutil_binary"],
>+                                         test_environment.config.ssl_config["ca_cert_path"])
>+        if kwargs["processes"] > 1:
>+            # With multiple processes, we would need a profile directory per process, but we
>+            # don't have an easy way to do that, so include the profile in the capabilties
>+            # directly instead. This means recreating it per session, which is slow
>+            options["profile"] = profile_creator.create_base64()
>+            profile = None
>+        else:
>+            profile = profile_creator.create()
>+            options["args"].extend(["--profile", profile.profile])
>+            test_environment.env_extras_cms.append(WdSpecProfile(profile))
>+
>         capabilities["moz:firefoxOptions"] = options
>+
>+        # This gets reused for firefox_android, but the environment setup
>+        # isn't required in that case
>+        if kwargs["binary"]:
>+            environ = get_environ(logger,
>+                                  kwargs["binary"],
>+                                  kwargs["debug_info"],
>+                                  kwargs["stylo_threads"],
>+                                  kwargs["headless"],
>+                                  kwargs["enable_webrender"],
>+                                  kwargs["chaos_mode_flags"])
>+            leak_report_file = setup_leak_report(kwargs["leak_check"], profile, environ)
>+
>+            # This doesn't work with wdspec tests
>+            # In particular tests can create a session without passing in the capabilites
>+            # and in those cases we get the default geckodriver profile which doesn't
>+            # guarantee zero network access
>+            del environ["MOZ_DISABLE_NONLOCAL_CONNECTIONS"]
>+            executor_kwargs["environ"] = environ
>+        else:
>+            if kwargs["headless"] and "--headless" not in options["args"]:
>+                options["args"].append("--headless")
>+            leak_report_file = None
>+
>+        executor_kwargs["stackfix_dir"] = kwargs["stackfix_dir"],
>+        executor_kwargs["leak_report_file"] = leak_report_file
>+        executor_kwargs["asan"] = run_info_data.get("asan")
>+
>     if kwargs["certutil_binary"] is None:
>         capabilities["acceptInsecureCerts"] = True
>     if capabilities:
>@@ -144,6 +203,7 @@ def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>     executor_kwargs["debug"] = run_info_data["debug"]
>     executor_kwargs["ccov"] = run_info_data.get("ccov", False)
>     executor_kwargs["browser_version"] = run_info_data.get("browser_version")
>+    executor_kwargs["debug_test"] = kwargs["debug_test"]
>     return executor_kwargs
> 
> 
>@@ -177,16 +237,11 @@ def run_info_extras(**kwargs):
>           "wasm": kwargs.get("wasm", True),
>           "verify": kwargs["verify"],
>           "headless": kwargs.get("headless", False) or "MOZ_HEADLESS" in os.environ,
>-          "sw-e10s": True,
>-          "fission": kwargs.get("enable_fission") or get_bool_pref("fission.autostart")}
>-
>-    # The value of `sw-e10s` defaults to whether the "parent_intercept"
>-    # implementation is enabled for the current build. This value, however,
>-    # can be overridden by explicitly setting the pref with the `--setpref` CLI
>-    # flag, which is checked here.
>-    sw_e10s_override = get_bool_pref_if_exists("dom.serviceWorkers.parent_intercept")
>-    if sw_e10s_override is not None:
>-        rv["sw-e10s"] = sw_e10s_override
>+          "fission": kwargs.get("enable_fission") or get_bool_pref("fission.autostart"),
>+          "sessionHistoryInParent": (kwargs.get("enable_fission") or
>+                                     get_bool_pref("fission.autostart") or
>+                                     get_bool_pref("fission.sessionHistoryInParent")),
>+          "swgl": get_bool_pref("gfx.webrender.software")}
> 
>     rv.update(run_info_browser_version(**kwargs))
> 
>@@ -208,11 +263,46 @@ def run_info_browser_version(**kwargs):
> 
> 
> def update_properties():
>-    return (["os", "debug", "webrender", "fission", "e10s", "sw-e10s", "processor"],
>+    return (["os", "debug", "webrender", "fission", "e10s", "processor", "swgl"],
>             {"os": ["version"], "processor": ["bits"]})
> 
> 
>-class FirefoxInstanceManager(object):
>+def get_environ(logger, binary, debug_info, stylo_threads, headless, enable_webrender,
>+                chaos_mode_flags=None):
>+    env = test_environment(xrePath=os.path.abspath(os.path.dirname(binary)),
>+                           debugger=debug_info is not None,
>+                           useLSan=True,
>+                           log=logger)
>+
>+    env["STYLO_THREADS"] = str(stylo_threads)
>+    if chaos_mode_flags is not None:
>+        env["MOZ_CHAOSMODE"] = str(chaos_mode_flags)
>+    if headless:
>+        env["MOZ_HEADLESS"] = "1"
>+    if enable_webrender:
>+        env["MOZ_WEBRENDER"] = "1"
>+        env["MOZ_ACCELERATED"] = "1"
>+    else:
>+        env["MOZ_WEBRENDER"] = "0"
>+    return env
>+
>+
>+def setup_leak_report(leak_check, profile, env):
>+    leak_report_file = None
>+    if leak_check:
>+        filename = "runtests_leaks_%s.log" % os.getpid()
>+        if profile is not None:
>+            leak_report_file = os.path.join(profile.profile, filename)
>+        else:
>+            leak_report_file = os.path.join(tempfile.gettempdir(), filename)
>+        if os.path.exists(leak_report_file):
>+            os.remove(leak_report_file)
>+        env["XPCOM_MEM_BLOAT_LOG"] = leak_report_file
>+
>+    return leak_report_file
>+
>+
>+class FirefoxInstanceManager:
>     __metaclass__ = ABCMeta
> 
>     def __init__(self, logger, binary, binary_args, profile_creator, debug_info,
>@@ -267,20 +357,8 @@ class FirefoxInstanceManager(object):
>         marionette_port = get_free_port()
>         profile.set_preferences({"marionette.port": marionette_port})
> 
>-        env = test_environment(xrePath=os.path.dirname(self.binary),
>-                               debugger=self.debug_info is not None,
>-                               useLSan=True, log=self.logger)
>-
>-        env["STYLO_THREADS"] = str(self.stylo_threads)
>-        if self.chaos_mode_flags is not None:
>-            env["MOZ_CHAOSMODE"] = str(self.chaos_mode_flags)
>-        if self.headless:
>-            env["MOZ_HEADLESS"] = "1"
>-        if self.enable_webrender:
>-            env["MOZ_WEBRENDER"] = "1"
>-            env["MOZ_ACCELERATED"] = "1"
>-        else:
>-            env["MOZ_WEBRENDER"] = "0"
>+        env = get_environ(self.logger, self.binary, self.debug_info, self.stylo_threads,
>+                          self.headless, self.enable_webrender, self.chaos_mode_flags)
> 
>         args = self.binary_args[:] if self.binary_args else []
>         args += [cmd_arg("marionette"), "about:blank"]
>@@ -289,26 +367,26 @@ class FirefoxInstanceManager(object):
>                                           args,
>                                           self.debug_info)
> 
>-        if self.leak_check:
>-            leak_report_file = os.path.join(profile.profile, "runtests_leaks_%s.log" % os.getpid())
>-            if os.path.exists(leak_report_file):
>-                os.remove(leak_report_file)
>-            env["XPCOM_MEM_BLOAT_LOG"] = leak_report_file
>-        else:
>-            leak_report_file = None
>-
>-        output_handler = OutputHandler(self.logger, self.stackfix_dir, self.symbols_path, self.asan)
>+        leak_report_file = setup_leak_report(self.leak_check, profile, env)
>+        output_handler = FirefoxOutputHandler(self.logger,
>+                                              cmd,
>+                                              stackfix_dir=self.stackfix_dir,
>+                                              symbols_path=self.symbols_path,
>+                                              asan=self.asan,
>+                                              leak_report_file=leak_report_file)
>         runner = FirefoxRunner(profile=profile,
>                                binary=cmd[0],
>                                cmdargs=cmd[1:],
>-                               env=cast_env(env),
>+                               env=env,
>                                process_class=ProcessHandler,
>                                process_args={"processOutputLine": [output_handler]})
>         instance = BrowserInstance(self.logger, runner, marionette_port,
>                                    output_handler, leak_report_file)
> 
>         self.logger.debug("Starting Firefox")
>-        runner.start(debug_args=debug_args, interactive=self.debug_info and self.debug_info.interactive)
>+        runner.start(debug_args=debug_args,
>+                     interactive=self.debug_info and self.debug_info.interactive)
>+        output_handler.after_process_start(runner.process_handler.pid)
>         self.logger.debug("Firefox Started")
> 
>         return instance
>@@ -330,6 +408,7 @@ class SingleInstanceManager(FirefoxInstanceManager):
>             if instance:
>                 instance.stop(force)
>                 instance.cleanup()
>+        self.base_profile.cleanup()
> 
> 
> class PreloadInstanceManager(FirefoxInstanceManager):
>@@ -352,15 +431,16 @@ class PreloadInstanceManager(FirefoxInstanceManager):
>         return self.current
> 
>     def teardown(self, force=False):
>-        for instance, skip_marionette in [(self.previous, False),
>-                                          (self.current, False),
>-                                          (self.pending, True)]:
>+        for instance, unused in [(self.previous, False),
>+                                 (self.current, False),
>+                                 (self.pending, True)]:
>             if instance:
>-                instance.stop(force, skip_marionette=skip_marionette)
>+                instance.stop(force, unused)
>                 instance.cleanup()
>+        self.base_profile.cleanup()
> 
> 
>-class BrowserInstance(object):
>+class BrowserInstance:
>     shutdown_timeout = 70
> 
>     def __init__(self, logger, runner, marionette_port, output_handler, leak_report_file):
>@@ -371,25 +451,35 @@ class BrowserInstance(object):
>         self.output_handler = output_handler
>         self.leak_report_file = leak_report_file
> 
>-    def stop(self, force=False, skip_marionette=False):
>-        """Stop Firefox"""
>+    def stop(self, force=False, unused=False):
>+        """Stop Firefox
>+
>+        :param force: Signal the firefox process without waiting for a clean shutdown
>+        :param unused: This instance was not used for running tests and so
>+                       doesn't have an active marionette session and doesn't require
>+                       output postprocessing.
>+        """
>         is_running = self.runner is not None and self.runner.is_running()
>         if is_running:
>             self.logger.debug("Stopping Firefox %s" % self.pid())
>             shutdown_methods = [(True, lambda: self.runner.wait(self.shutdown_timeout)),
>-                                (False, lambda: self.runner.stop(signal.SIGTERM)),
>-                                (False, lambda: self.runner.stop(signal.SIGKILL))]
>-            if skip_marionette:
>+                                (False, lambda: self.runner.stop(signal.SIGTERM,
>+                                                                 self.shutdown_timeout))]
>+            if hasattr(signal, "SIGKILL"):
>+                shutdown_methods.append((False, lambda: self.runner.stop(signal.SIGKILL,
>+                                                                         self.shutdown_timeout)))
>+            if unused or force:
>+                # Don't wait for the instance to close itself
>                 shutdown_methods = shutdown_methods[1:]
>             try:
>                 # For Firefox we assume that stopping the runner prompts the
>                 # browser to shut down. This allows the leak log to be written
>-                for clean, stop_f in shutdown_methods:
>-                    if not force or not clean:
>-                        retcode = stop_f()
>-                        if retcode is not None:
>-                            self.logger.info("Browser exited with return code %s" % retcode)
>-                            break
>+                for i, (clean, stop_f) in enumerate(shutdown_methods):
>+                    self.logger.debug("Shutting down attempt %i/%i" % (i + 1, len(shutdown_methods)))
>+                    retcode = stop_f()
>+                    if retcode is not None:
>+                        self.logger.info("Browser exited with return code %s" % retcode)
>+                        break
>             except OSError:
>                 # This can happen on Windows if the process is already dead
>                 pass
>@@ -397,8 +487,8 @@ class BrowserInstance(object):
>             # The browser was already stopped, which we assume was a crash
>             # TODO: Should we check the exit code here?
>             clean = False
>-        if not skip_marionette:
>-            self.output_handler.after_stop(clean_shutdown=clean)
>+        if not unused:
>+            self.output_handler.after_process_stop(clean_shutdown=clean)
> 
>     def pid(self):
>         if self.runner.process_handler is None:
>@@ -415,12 +505,13 @@ class BrowserInstance(object):
>         return False
> 
>     def cleanup(self):
>-        # mozprofile handles deleting the profile when the refcount reaches 0
>+        self.runner.cleanup()
>         self.runner = None
> 
> 
>-class OutputHandler(object):
>-    def __init__(self, logger, stackfix_dir, symbols_path, asan):
>+class FirefoxOutputHandler(OutputHandler):
>+    def __init__(self, logger, command, symbols_path=None, stackfix_dir=None, asan=False,
>+                 leak_report_file=None):
>         """Filter for handling Firefox process output.
> 
>         This receives Firefox process output in the __call__ function, does
>@@ -431,9 +522,7 @@ class OutputHandler(object):
>         of the output handlers.
>         """
> 
>-        self.logger = logger
>-        # These are filled in after setup() is called
>-        self.instance = None
>+        super().__init__(logger, command)
> 
>         self.symbols_path = symbols_path
>         if stackfix_dir:
>@@ -445,21 +534,18 @@ class OutputHandler(object):
>         else:
>             self.stack_fixer = None
>         self.asan = asan
>+        self.leak_report_file = leak_report_file
> 
>+        # These are filled in after configure_handlers() is called
>         self.lsan_handler = None
>         self.mozleak_allowed = None
>         self.mozleak_thresholds = None
>         self.group_metadata = {}
> 
>-        self.line_buffer = []
>-        self.setup_ran = False
>-
>-    def setup(self, instance=None, group_metadata=None, lsan_disabled=False,
>-              lsan_allowed=None, lsan_max_stack_depth=None, mozleak_allowed=None,
>-              mozleak_thresholds=None, **kwargs):
>+    def start(self, group_metadata=None, lsan_disabled=False, lsan_allowed=None,
>+              lsan_max_stack_depth=None, mozleak_allowed=None, mozleak_thresholds=None,
>+              **kwargs):
>         """Configure the output handler"""
>-        self.instance = instance
>-
>         if group_metadata is None:
>             group_metadata = {}
>         self.group_metadata = group_metadata
>@@ -475,18 +561,13 @@ class OutputHandler(object):
>                                                   allowAll=lsan_disabled)
>         else:
>             self.lsan_handler = None
>+        super().start()
> 
>-        self.setup_ran = True
>-
>-        for line in self.line_buffer:
>-            self.__call__(line)
>-        self.line_buffer = []
>-
>-    def after_stop(self, clean_shutdown=True):
>-        self.logger.info("PROCESS LEAKS %s" % self.instance.leak_report_file)
>+    def after_process_stop(self, clean_shutdown=True):
>+        super().after_process_stop(clean_shutdown)
>         if self.lsan_handler:
>             self.lsan_handler.process()
>-        if self.instance.leak_report_file is not None:
>+        if self.leak_report_file is not None:
>             if not clean_shutdown:
>                 # If we didn't get a clean shutdown there probably isn't a leak report file
>                 self.logger.warning("Firefox didn't exit cleanly, not processing leak logs")
>@@ -494,21 +575,24 @@ class OutputHandler(object):
>                 # We have to ignore missing leaks in the tab because it can happen that the
>                 # content process crashed and in that case we don't want the test to fail.
>                 # Ideally we would record which content process crashed and just skip those.
>+                self.logger.info("PROCESS LEAKS %s" % self.leak_report_file)
>                 mozleak.process_leak_log(
>-                    self.instance.leak_report_file,
>+                    self.leak_report_file,
>                     leak_thresholds=self.mozleak_thresholds,
>                     ignore_missing_leaks=["tab", "gmplugin"],
>                     log=self.logger,
>                     stack_fixer=self.stack_fixer,
>                     scope=self.group_metadata.get("scope"),
>                     allowed=self.mozleak_allowed)
>+            if os.path.exists(self.leak_report_file):
>+                os.unlink(self.leak_report_file)
> 
>     def __call__(self, line):
>         """Write a line of output from the firefox process to the log"""
>         if b"GLib-GObject-CRITICAL" in line:
>             return
>         if line:
>-            if not self.setup_ran:
>+            if self.state < OutputHandlerState.AFTER_HANDLER_START:
>                 self.line_buffer.append(line)
>                 return
>             data = line.decode("utf8", "replace")
>@@ -517,14 +601,12 @@ class OutputHandler(object):
>             if self.lsan_handler:
>                 data = self.lsan_handler.log(data)
>             if data is not None:
>-                self.logger.process_output(self.instance and
>-                                           self.instance.runner.process_handler and
>-                                           self.instance.runner.process_handler.pid,
>+                self.logger.process_output(self.pid,
>                                            data,
>-                                           command=" ".join(self.instance.runner.command))
>+                                           command=" ".join(self.command))
> 
> 
>-class ProfileCreator(object):
>+class ProfileCreator:
>     def __init__(self, logger, prefs_root, config, test_type, extra_prefs, e10s,
>                  enable_fission, browser_channel, binary, certutil_binary, ca_certificate_path):
>         self.logger = logger
>@@ -540,18 +622,38 @@ class ProfileCreator(object):
>         self.certutil_binary = certutil_binary
>         self.ca_certificate_path = ca_certificate_path
> 
>-    def create(self):
>+    def create(self, **kwargs):
>         """Create a Firefox profile and return the mozprofile Profile object pointing at that
>-        profile"""
>+        profile
>+
>+        :param kwargs: Additional arguments to pass into the profile constructor
>+        """
>         preferences = self._load_prefs()
> 
>-        profile = FirefoxProfile(preferences=preferences)
>+        profile = FirefoxProfile(preferences=preferences,
>+                                 restore=False,
>+                                 **kwargs)
>         self._set_required_prefs(profile)
>         if self.ca_certificate_path is not None:
>             self._setup_ssl(profile)
> 
>         return profile
> 
>+    def create_base64(self, **kwargs):
>+        profile = self.create(**kwargs)
>+        try:
>+            with io.BytesIO() as buf:
>+                with zipfile.ZipFile(buf, "w", compression=zipfile.ZIP_DEFLATED) as zipf:
>+                    for dirpath, _, filenames in os.walk(profile.profile):
>+                        for filename in filenames:
>+                            src_path = os.path.join(dirpath, filename)
>+                            dest_path = os.path.relpath(src_path, profile.profile)
>+                            with open(src_path, "rb") as f:
>+                                zipf.writestr(dest_path, f.read())
>+                return base64.b64encode(buf.getvalue()).decode("ascii").strip()
>+        finally:
>+            profile.cleanup()
>+
>     def _load_prefs(self):
>         prefs = Preferences()
> 
>@@ -641,14 +743,13 @@ class ProfileCreator(object):
> 
> 
>         env[env_var] = (os.path.pathsep.join([certutil_dir, env[env_var]])
>-                        if env_var in env else certutil_dir).encode(
>-                            sys.getfilesystemencoding() or 'utf-8', 'replace')
>+                        if env_var in env else certutil_dir)
> 
>         def certutil(*args):
>             cmd = [self.certutil_binary] + list(args)
>             self.logger.process_output("certutil",
>                                        subprocess.check_output(cmd,
>-                                                               env=cast_env(env),
>+                                                               env=env,
>                                                                stderr=subprocess.STDOUT),
>                                        " ".join(cmd))
> 
>@@ -670,7 +771,6 @@ class ProfileCreator(object):
>         certutil("-L", "-d", cert_db_path)
> 
> 
>-
> class FirefoxBrowser(Browser):
>     init_timeout = 70
> 
>@@ -679,7 +779,8 @@ class FirefoxBrowser(Browser):
>                  ca_certificate_path=None, e10s=False, enable_webrender=False, enable_fission=False,
>                  stackfix_dir=None, binary_args=None, timeout_multiplier=None, leak_check=False,
>                  asan=False, stylo_threads=1, chaos_mode_flags=None, config=None,
>-                 browser_channel="nightly", headless=None, preload_browser=False, **kwargs):
>+                 browser_channel="nightly", headless=None, preload_browser=False,
>+                 specialpowers_path=None, **kwargs):
>         Browser.__init__(self, logger)
> 
>         self.logger = logger
>@@ -688,6 +789,7 @@ class FirefoxBrowser(Browser):
>             self.init_timeout = self.init_timeout * timeout_multiplier
> 
>         self.instance = None
>+        self._settings = None
> 
>         self.stackfix_dir = stackfix_dir
>         self.symbols_path = symbols_path
>@@ -696,6 +798,8 @@ class FirefoxBrowser(Browser):
>         self.asan = asan
>         self.leak_check = leak_check
> 
>+        self.specialpowers_path = specialpowers_path
>+
>         profile_creator = ProfileCreator(logger,
>                                          prefs_root,
>                                          config,
>@@ -726,19 +830,19 @@ class FirefoxBrowser(Browser):
>                                                      symbols_path,
>                                                      asan)
> 
>-
>     def settings(self, test):
>-        return {"check_leaks": self.leak_check and not test.leaks,
>-                "lsan_disabled": test.lsan_disabled,
>-                "lsan_allowed": test.lsan_allowed,
>-                "lsan_max_stack_depth": test.lsan_max_stack_depth,
>-                "mozleak_allowed": self.leak_check and test.mozleak_allowed,
>-                "mozleak_thresholds": self.leak_check and test.mozleak_threshold}
>+        self._settings = {"check_leaks": self.leak_check and not test.leaks,
>+                          "lsan_disabled": test.lsan_disabled,
>+                          "lsan_allowed": test.lsan_allowed,
>+                          "lsan_max_stack_depth": test.lsan_max_stack_depth,
>+                          "mozleak_allowed": self.leak_check and test.mozleak_allowed,
>+                          "mozleak_thresholds": self.leak_check and test.mozleak_threshold,
>+                          "special_powers": self.specialpowers_path and test.url_base == "/_mozilla/"}
>+        return self._settings
> 
>     def start(self, group_metadata=None, **kwargs):
>         self.instance = self.instance_manager.get()
>-        self.instance.output_handler.setup(self.instance,
>-                                           group_metadata,
>+        self.instance.output_handler.start(group_metadata,
>                                            **kwargs)
> 
>     def stop(self, force=False):
>@@ -756,7 +860,11 @@ class FirefoxBrowser(Browser):
> 
>     def executor_browser(self):
>         assert self.instance is not None
>-        return ExecutorBrowser, {"marionette_port": self.instance.marionette_port}
>+        extensions = []
>+        if self._settings.get("special_powers", False):
>+            extensions.append(self.specialpowers_path)
>+        return ExecutorBrowser, {"marionette_port": self.instance.marionette_port,
>+                                 "extensions": extensions}
> 
>     def check_crash(self, process, test):
>         dump_dir = os.path.join(self.instance.runner.profile.profile, "minidumps")
>@@ -771,3 +879,39 @@ class FirefoxBrowser(Browser):
>         except IOError:
>             self.logger.warning("Looking for crash dump files failed")
>             return False
>+
>+
>+class FirefoxWdSpecBrowser(NullBrowser):
>+    def __init__(self, logger, leak_check=False, **kwargs):
>+        super().__init__(logger, **kwargs)
>+        self.leak_check = leak_check
>+
>+    def settings(self, test):
>+        return {"check_leaks": self.leak_check and not test.leaks,
>+                "lsan_disabled": test.lsan_disabled,
>+                "lsan_allowed": test.lsan_allowed,
>+                "lsan_max_stack_depth": test.lsan_max_stack_depth,
>+                "mozleak_allowed": self.leak_check and test.mozleak_allowed,
>+                "mozleak_thresholds": self.leak_check and test.mozleak_threshold}
>+
>+
>+class GeckoDriverServer(WebDriverServer):
>+    output_handler_cls = FirefoxOutputHandler
>+
>+    def __init__(self, logger, marionette_port=2828, binary="geckodriver",
>+                 host="127.0.0.1", port=None, env=None, args=None):
>+        if env is None:
>+            env = os.environ.copy()
>+        env["RUST_BACKTRACE"] = "1"
>+        WebDriverServer.__init__(self, logger, binary,
>+                                 host=host,
>+                                 port=port,
>+                                 env=env,
>+                                 args=args)
>+        self.marionette_port = marionette_port
>+
>+    def make_command(self):
>+        return [self.binary,
>+                "--marionette-port", str(self.marionette_port),
>+                "--host", self.host,
>+                "--port", str(self.port)] + self._args
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/ie.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/ie.py
>index 78c22b909acf..c851daf0b63c 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/ie.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/ie.py
>@@ -1,12 +1,11 @@
>-from .base import Browser, ExecutorBrowser, require_arg
>-from .base import get_timeout_multiplier   # noqa: F401
>-from ..webdriver_server import InternetExplorerDriverServer
>+from .base import require_arg
>+from .base import NullBrowser, get_timeout_multiplier  # noqa: F401
> from ..executors import executor_kwargs as base_executor_kwargs
> from ..executors.executorinternetexplorer import InternetExplorerDriverWdspecExecutor  # noqa: F401
> 
> __wptrunner__ = {"product": "ie",
>                  "check_args": "check_args",
>-                 "browser": "InternetExplorerBrowser",
>+                 "browser": "NullBrowser",
>                  "executor": {"wdspec": "InternetExplorerDriverWdspecExecutor"},
>                  "browser_kwargs": "browser_kwargs",
>                  "executor_kwargs": "executor_kwargs",
>@@ -18,18 +17,17 @@ __wptrunner__ = {"product": "ie",
> def check_args(**kwargs):
>     require_arg(kwargs, "webdriver_binary")
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {"webdriver_binary": kwargs["webdriver_binary"],
>             "webdriver_args": kwargs.get("webdriver_args")}
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>     options = {}
>     options["requireWindowFocus"] = True
>     capabilities = {}
>     capabilities["se:ieOptions"] = options
>-    executor_kwargs = base_executor_kwargs(test_type, server_config,
>-                                           cache_manager, run_info_data, **kwargs)
>+    executor_kwargs = base_executor_kwargs(test_type, test_environment, run_info_data, **kwargs)
>     executor_kwargs["close_after_done"] = True
>     executor_kwargs["capabilities"] = capabilities
>     return executor_kwargs
>@@ -39,35 +37,3 @@ def env_extras(**kwargs):
> 
> def env_options():
>     return {"supports_debugger": False}
>-
>-class InternetExplorerBrowser(Browser):
>-    used_ports = set()
>-
>-    def __init__(self, logger, webdriver_binary, webdriver_args=None):
>-        Browser.__init__(self, logger)
>-        self.server = InternetExplorerDriverServer(self.logger,
>-                                                   binary=webdriver_binary,
>-                                                   args=webdriver_args)
>-        self.webdriver_host = "localhost"
>-        self.webdriver_port = self.server.port
>-
>-    def start(self, **kwargs):
>-        self.server.start()
>-
>-    def stop(self, force=False):
>-        self.server.stop(force=force)
>-
>-    def pid(self):
>-        return self.server.pid
>-
>-    def is_alive(self):
>-        # TODO(ato): This only indicates the server is alive,
>-        # and doesn't say anything about whether a browser session
>-        # is active.
>-        return self.server.is_alive()
>-
>-    def cleanup(self):
>-        self.stop()
>-
>-    def executor_browser(self):
>-        return ExecutorBrowser, {"webdriver_url": self.server.url}
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/opera.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/opera.py
>index 805fedee636c..f3a2929ce8eb 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/opera.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/opera.py
>@@ -1,4 +1,5 @@
> from .base import Browser, ExecutorBrowser, require_arg
>+from .base import NullBrowser  # noqa: F401
> from .base import get_timeout_multiplier   # noqa: F401
> from ..webdriver_server import OperaDriverServer
> from ..executors import executor_kwargs as base_executor_kwargs
>@@ -9,7 +10,8 @@ from ..executors.executoropera import OperaDriverWdspecExecutor  # noqa: F401
> 
> __wptrunner__ = {"product": "opera",
>                  "check_args": "check_args",
>-                 "browser": "OperaBrowser",
>+                 "browser": {None: "OperaBrowser",
>+                             "wdspec": "NullBrowser"},
>                  "executor": {"testharness": "SeleniumTestharnessExecutor",
>                               "reftest": "SeleniumRefTestExecutor",
>                               "wdspec": "OperaDriverWdspecExecutor"},
>@@ -24,18 +26,17 @@ def check_args(**kwargs):
>     require_arg(kwargs, "webdriver_binary")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {"binary": kwargs["binary"],
>             "webdriver_binary": kwargs["webdriver_binary"],
>             "webdriver_args": kwargs.get("webdriver_args")}
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>     from selenium.webdriver import DesiredCapabilities
> 
>-    executor_kwargs = base_executor_kwargs(test_type, server_config,
>-                                           cache_manager, run_info_data, **kwargs)
>+    executor_kwargs = base_executor_kwargs(test_type, test_environment, run_info_data, **kwargs)
>     executor_kwargs["close_after_done"] = True
>     capabilities = dict(DesiredCapabilities.OPERA.items())
>     capabilities.setdefault("operaOptions", {})["prefs"] = {
>@@ -71,7 +72,7 @@ class OperaBrowser(Browser):
>     """
> 
>     def __init__(self, logger, binary, webdriver_binary="operadriver",
>-                 webdriver_args=None):
>+                 webdriver_args=None, **kwargs):
>         """Creates a new representation of Opera.  The `binary` argument gives
>         the browser binary to use for testing."""
>         Browser.__init__(self, logger)
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/safari.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/safari.py
>index cb2b175d4dfb..20a5475acf0b 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/safari.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/safari.py
>@@ -1,4 +1,11 @@
>+import os
>+import plistlib
>+from distutils.spawn import find_executable
>+
>+import psutil
>+
> from .base import Browser, ExecutorBrowser, require_arg
>+from .base import NullBrowser  # noqa: F401
> from .base import get_timeout_multiplier   # noqa: F401
> from ..webdriver_server import SafariDriverServer
> from ..executors import executor_kwargs as base_executor_kwargs
>@@ -10,7 +17,8 @@ from ..executors.executorsafari import SafariDriverWdspecExecutor  # noqa: F401
> 
> __wptrunner__ = {"product": "safari",
>                  "check_args": "check_args",
>-                 "browser": "SafariBrowser",
>+                 "browser": {None: "SafariBrowser",
>+                             "wdspec": "NullBrowser"},
>                  "executor": {"testharness": "WebDriverTestharnessExecutor",
>                               "reftest": "WebDriverRefTestExecutor",
>                               "wdspec": "SafariDriverWdspecExecutor",
>@@ -26,15 +34,14 @@ def check_args(**kwargs):
>     require_arg(kwargs, "webdriver_binary")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {"webdriver_binary": kwargs["webdriver_binary"],
>-            "webdriver_args": kwargs.get("webdriver_args")}
>+            "webdriver_args": kwargs.get("webdriver_args"),
>+            "kill_safari": kwargs.get("kill_safari", False)}
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>-                    **kwargs):
>-    executor_kwargs = base_executor_kwargs(test_type, server_config,
>-                                           cache_manager, run_info_data, **kwargs)
>+def executor_kwargs(logger, test_type, test_environment, run_info_data, **kwargs):
>+    executor_kwargs = base_executor_kwargs(test_type, test_environment, run_info_data, **kwargs)
>     executor_kwargs["close_after_done"] = True
>     executor_kwargs["capabilities"] = {}
>     if test_type == "testharness":
>@@ -58,15 +65,60 @@ class SafariBrowser(Browser):
>     ``wptrunner.webdriver.SafariDriverServer``.
>     """
> 
>-    def __init__(self, logger, webdriver_binary, webdriver_args=None):
>+    def __init__(self, logger, webdriver_binary, webdriver_args=None, kill_safari=False, **kwargs):
>         """Creates a new representation of Safari.  The `webdriver_binary`
>         argument gives the WebDriver binary to use for testing. (The browser
>         binary location cannot be specified, as Safari and SafariDriver are
>-        coupled.)"""
>+        coupled.) If `kill_safari` is True, then `Browser.stop` will stop Safari."""
>         Browser.__init__(self, logger)
>         self.server = SafariDriverServer(self.logger,
>                                          binary=webdriver_binary,
>                                          args=webdriver_args)
>+        if "/" not in webdriver_binary:
>+            wd_path = find_executable(webdriver_binary)
>+        else:
>+            wd_path = webdriver_binary
>+        self.safari_path = self._findAssociatedSafariExecutable(wd_path)
>+
>+        logger.debug("WebDriver executable path: %s" % wd_path)
>+        logger.debug("Safari executable path: %s" % self.safari_path)
>+
>+        self.kill_safari = kill_safari
>+
>+    def _findAssociatedSafariExecutable(self, wd_path):
>+        bundle_paths = [
>+            os.path.join(os.path.dirname(wd_path), "..", ".."),  # bundled Safari (e.g. STP)
>+            os.path.join(os.path.dirname(wd_path), "Safari.app"),  # local Safari build
>+            "/Applications/Safari.app",  # system Safari
>+        ]
>+
>+        for bundle_path in bundle_paths:
>+            info_path = os.path.join(bundle_path, "Contents", "Info.plist")
>+            if not os.path.isfile(info_path):
>+                continue
>+
>+            with open(info_path, "rb") as fp:
>+                info = plistlib.load(fp)
>+
>+            # check we have a Safari family bundle
>+            if "CFBundleIdentifier" not in info:
>+                continue
>+            ident = info["CFBundleIdentifier"]
>+            if not isinstance(ident, str) or not ident.startswith("com.apple.Safari"):
>+                continue
>+
>+            # get the executable name
>+            if "CFBundleExecutable" not in info:
>+                continue
>+            exe = info["CFBundleExecutable"]
>+            if not isinstance(exe, str):
>+                continue
>+
>+            exe_path = os.path.join(bundle_path, "Contents", "MacOS", exe)
>+            if not os.path.isfile(exe_path):
>+                continue
>+
>+            return exe_path
> 
>     def start(self, **kwargs):
>         self.server.start(block=False)
>@@ -74,6 +126,20 @@ class SafariBrowser(Browser):
>     def stop(self, force=False):
>         self.server.stop(force=force)
> 
>+        if self.kill_safari:
>+            self.logger.debug("Going to stop Safari")
>+            for proc in psutil.process_iter(attrs=["exe"]):
>+                if proc.info["exe"] is not None and os.path.samefile(proc.info["exe"], self.safari_path):
>+                    self.logger.debug("Stopping Safari %s" % proc.pid)
>+                    try:
>+                        proc.terminate()
>+                        try:
>+                            proc.wait(10)
>+                        except psutil.TimeoutExpired:
>+                            proc.kill()
>+                    except psutil.NoSuchProcess:
>+                        pass
>+
>     def pid(self):
>         return self.server.pid
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/sauce.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/sauce.py
>index c57ac942ed4e..491319917599 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/sauce.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/sauce.py
>@@ -12,7 +12,7 @@ import time
> 
> import requests
> 
>-from six.moves import cStringIO as StringIO
>+from io import StringIO
> 
> from .base import Browser, ExecutorBrowser, require_arg
> from .base import get_timeout_multiplier   # noqa: F401
>@@ -95,16 +95,15 @@ def check_args(**kwargs):
>     require_arg(kwargs, "sauce_key")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     sauce_config = get_sauce_config(**kwargs)
> 
>     return {"sauce_config": sauce_config}
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>-    executor_kwargs = base_executor_kwargs(test_type, server_config,
>-                                           cache_manager, run_info_data, **kwargs)
>+    executor_kwargs = base_executor_kwargs(test_type, test_environment, run_info_data, **kwargs)
> 
>     executor_kwargs["capabilities"] = get_capabilities(**kwargs)
> 
>@@ -228,7 +227,7 @@ class SauceException(Exception):
> class SauceBrowser(Browser):
>     init_timeout = 300
> 
>-    def __init__(self, logger, sauce_config):
>+    def __init__(self, logger, sauce_config, **kwargs):
>         Browser.__init__(self, logger)
>         self.sauce_config = sauce_config
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/servo.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/servo.py
>index b9476540ac7c..1791c1da2706 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/servo.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/servo.py
>@@ -33,7 +33,7 @@ def check_args(**kwargs):
>     require_arg(kwargs, "binary")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {
>         "binary": kwargs["binary"],
>         "debug_info": kwargs["debug_info"],
>@@ -43,10 +43,9 @@ def browser_kwargs(test_type, run_info_data, config, **kwargs):
>     }
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>-    rv = base_executor_kwargs(test_type, server_config,
>-                              cache_manager, run_info_data, **kwargs)
>+    rv = base_executor_kwargs(test_type, test_environment, run_info_data, **kwargs)
>     rv["pause_after_test"] = kwargs["pause_after_test"]
>     if test_type == "wdspec":
>         rv["capabilities"] = {}
>@@ -71,7 +70,7 @@ def update_properties():
> 
> class ServoBrowser(NullBrowser):
>     def __init__(self, logger, binary, debug_info=None, binary_args=None,
>-                 user_stylesheets=None, ca_certificate_path=None):
>+                 user_stylesheets=None, ca_certificate_path=None, **kwargs):
>         NullBrowser.__init__(self, logger)
>         self.binary = binary
>         self.debug_info = debug_info
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/servodriver.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/servodriver.py
>index 43794e41706d..9a6a1a402b36 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/servodriver.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/servodriver.py
>@@ -6,12 +6,16 @@ from mozprocess import ProcessHandler
> 
> from tools.serve.serve import make_hosts_file
> 
>-from .base import Browser, require_arg, get_free_port, browser_command, ExecutorBrowser
>+from .base import (Browser,
>+                   ExecutorBrowser,
>+                   OutputHandler,
>+                   require_arg,
>+                   get_free_port,
>+                   browser_command)
> from .base import get_timeout_multiplier   # noqa: F401
> from ..executors import executor_kwargs as base_executor_kwargs
> from ..executors.executorservodriver import (ServoWebDriverTestharnessExecutor,  # noqa: F401
>                                              ServoWebDriverRefTestExecutor)  # noqa: F401
>-from ..process import cast_env
> 
> here = os.path.dirname(__file__)
> 
>@@ -36,7 +40,7 @@ def check_args(**kwargs):
>     require_arg(kwargs, "binary")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {
>         "binary": kwargs["binary"],
>         "binary_args": kwargs["binary_args"],
>@@ -47,9 +51,8 @@ def browser_kwargs(test_type, run_info_data, config, **kwargs):
>     }
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data, **kwargs):
>-    rv = base_executor_kwargs(test_type, server_config,
>-                              cache_manager, run_info_data, **kwargs)
>+def executor_kwargs(logger, test_type, test_environment, run_info_data, **kwargs):
>+    rv = base_executor_kwargs(test_type, test_environment, run_info_data, **kwargs)
>     return rv
> 
> 
>@@ -77,7 +80,8 @@ class ServoWebDriverBrowser(Browser):
>     init_timeout = 300  # Large timeout for cases where we're booting an Android emulator
> 
>     def __init__(self, logger, binary, debug_info=None, webdriver_host="127.0.0.1",
>-                 server_config=None, binary_args=None, user_stylesheets=None, headless=None):
>+                 server_config=None, binary_args=None,
>+                 user_stylesheets=None, headless=None, **kwargs):
>         Browser.__init__(self, logger)
>         self.binary = binary
>         self.binary_args = binary_args or []
>@@ -91,6 +95,7 @@ class ServoWebDriverBrowser(Browser):
>         self.user_stylesheets = user_stylesheets if user_stylesheets else []
>         self.headless = headless if headless else False
>         self.ca_certificate_path = server_config.ssl_config["ca_cert_path"]
>+        self.output_handler = None
> 
>     def start(self, **kwargs):
>         self.webdriver_port = get_free_port()
>@@ -129,13 +134,16 @@ class ServoWebDriverBrowser(Browser):
>         self.command = debug_args + self.command
> 
>         if not self.debug_info or not self.debug_info.interactive:
>+            self.output_handler = OutputHandler(self.logger, self.command)
>             self.proc = ProcessHandler(self.command,
>                                        processOutputLine=[self.on_output],
>-                                       env=cast_env(env),
>+                                       env=env,
>                                        storeOutput=False)
>             self.proc.run()
>+            self.output_handler.after_process_start(self.proc.pid)
>+            self.output_handler.start()
>         else:
>-            self.proc = subprocess.Popen(self.command, env=cast_env(env))
>+            self.proc = subprocess.Popen(self.command, env=env)
> 
>         self.logger.debug("Servo Started")
> 
>@@ -147,6 +155,8 @@ class ServoWebDriverBrowser(Browser):
>             except OSError:
>                 # This can happen on Windows if the process is already dead
>                 pass
>+        if self.output_handler is not None:
>+            self.output_handler.after_process_stop()
> 
>     def pid(self):
>         if self.proc is None:
>@@ -157,12 +167,6 @@ class ServoWebDriverBrowser(Browser):
>         except AttributeError:
>             return None
> 
>-    def on_output(self, line):
>-        """Write a line of output from the process to the log"""
>-        self.logger.process_output(self.pid(),
>-                                   line.decode("utf8", "replace"),
>-                                   command=" ".join(self.command))
>-
>     def is_alive(self):
>         return self.proc.poll() is None
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/webkit.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/webkit.py
>index da93cf164399..ad24771ac9ce 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/webkit.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/browsers/webkit.py
>@@ -1,5 +1,5 @@
> from .base import Browser, ExecutorBrowser, require_arg
>-from .base import get_timeout_multiplier, certificate_domain_list  # noqa: F401
>+from .base import NullBrowser, get_timeout_multiplier, certificate_domain_list  # noqa: F401
> from ..executors import executor_kwargs as base_executor_kwargs
> from ..executors.executorwebdriver import (WebDriverTestharnessExecutor,  # noqa: F401
>                                            WebDriverRefTestExecutor,  # noqa: F401
>@@ -10,7 +10,8 @@ from ..webdriver_server import WebKitDriverServer
> 
> __wptrunner__ = {"product": "webkit",
>                  "check_args": "check_args",
>-                 "browser": "WebKitBrowser",
>+                 "browser": {None: "WebKitBrowser",
>+                             "wdspec": "NullBrowser"},
>                  "browser_kwargs": "browser_kwargs",
>                  "executor": {"testharness": "WebDriverTestharnessExecutor",
>                               "reftest": "WebDriverRefTestExecutor",
>@@ -29,7 +30,7 @@ def check_args(**kwargs):
>     require_arg(kwargs, "webkit_port")
> 
> 
>-def browser_kwargs(test_type, run_info_data, config, **kwargs):
>+def browser_kwargs(logger, test_type, run_info_data, config, **kwargs):
>     return {"binary": kwargs["binary"],
>             "webdriver_binary": kwargs["webdriver_binary"],
>             "webdriver_args": kwargs.get("webdriver_args")}
>@@ -54,12 +55,11 @@ def capabilities_for_port(server_config, **kwargs):
>     return {}
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>+def executor_kwargs(logger, test_type, test_environment, run_info_data,
>                     **kwargs):
>-    executor_kwargs = base_executor_kwargs(test_type, server_config,
>-                                           cache_manager, run_info_data, **kwargs)
>+    executor_kwargs = base_executor_kwargs(test_type, test_environment, run_info_data, **kwargs)
>     executor_kwargs["close_after_done"] = True
>-    executor_kwargs["capabilities"] = capabilities_for_port(server_config,
>+    executor_kwargs["capabilities"] = capabilities_for_port(test_environment.config,
>                                                             **kwargs)
>     return executor_kwargs
> 
>@@ -82,7 +82,7 @@ class WebKitBrowser(Browser):
>     """
> 
>     def __init__(self, logger, binary, webdriver_binary=None,
>-                 webdriver_args=None):
>+                 webdriver_args=None, **kwargs):
>         Browser.__init__(self, logger)
>         self.binary = binary
>         self.server = WebKitDriverServer(self.logger, binary=webdriver_binary,
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/config.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/config.py
>index d46beb8e71db..8a9bdbf730d6 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/config.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/config.py
>@@ -1,11 +1,12 @@
>-from six.moves.configparser import SafeConfigParser
>+from configparser import ConfigParser
> import os
> import sys
> from collections import OrderedDict
>+from typing import Any, Dict
> 
> here = os.path.dirname(__file__)
> 
>-class ConfigDict(dict):
>+class ConfigDict(Dict[str, Any]):
>     def __init__(self, base_path, *args, **kwargs):
>         self.base_path = base_path
>         dict.__init__(self, *args, **kwargs)
>@@ -20,7 +21,7 @@ class ConfigDict(dict):
> def read(config_path):
>     config_path = os.path.abspath(config_path)
>     config_root = os.path.dirname(config_path)
>-    parser = SafeConfigParser()
>+    parser = ConfigParser()
>     success = parser.read(config_path)
>     assert config_path in success, success
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/environment.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/environment.py
>index 2527d26d391d..3fe971456ed6 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/environment.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/environment.py
>@@ -1,15 +1,14 @@
> import json
> import os
>-import multiprocessing
> import signal
> import socket
> import sys
> import time
>-from six import iteritems
> 
>-from mozlog import get_default_logger, handlers, proxy
>+from mozlog import get_default_logger, handlers
> 
>-from .wptlogging import LogLevelRewriter
>+from . import mpcontext
>+from .wptlogging import LogLevelRewriter, QueueHandler, LogQueueThread
> 
> here = os.path.dirname(__file__)
> repo_root = os.path.abspath(os.path.join(here, os.pardir, os.pardir, os.pardir))
>@@ -50,24 +49,58 @@ class TestEnvironmentError(Exception):
>     pass
> 
> 
>+def get_server_logger():
>+    logger = get_default_logger(component="wptserve")
>+    log_filter = handlers.LogLevelFilter(lambda x: x, "info")
>+    # Downgrade errors to warnings for the server
>+    log_filter = LogLevelRewriter(log_filter, ["error"], "warning")
>+    logger.component_filter = log_filter
>+    return logger
>+
>+
>+class ProxyLoggingContext:
>+    """Context manager object that handles setup and teardown of a log queue
>+    for handling logging messages from wptserve."""
>+
>+    def __init__(self, logger):
>+        mp_context = mpcontext.get_context()
>+        self.log_queue = mp_context.Queue()
>+        self.logging_thread = LogQueueThread(self.log_queue, logger)
>+        self.logger_handler = QueueHandler(self.log_queue)
>+
>+    def __enter__(self):
>+        self.logging_thread.start()
>+        return self.logger_handler
>+
>+    def __exit__(self, *args):
>+        self.log_queue.put(None)
>+        # Wait for thread to shut down but not for too long since it's a daemon
>+        self.logging_thread.join(1)
>+
>+
> class TestEnvironment(object):
>     """Context manager that owns the test environment i.e. the http and
>     websockets servers"""
>     def __init__(self, test_paths, testharness_timeout_multipler,
>-                 pause_after_test, debug_info, options, ssl_config, env_extras,
>+                 pause_after_test, debug_test, debug_info, options, ssl_config, env_extras,
>                  enable_quic=False, mojojs_path=None):
>+
>         self.test_paths = test_paths
>         self.server = None
>         self.config_ctx = None
>         self.config = None
>+        self.server_logger = get_server_logger()
>+        self.server_logging_ctx = ProxyLoggingContext(self.server_logger)
>         self.testharness_timeout_multipler = testharness_timeout_multipler
>         self.pause_after_test = pause_after_test
>+        self.debug_test = debug_test
>         self.test_server_port = options.pop("test_server_port", True)
>         self.debug_info = debug_info
>         self.options = options if options is not None else {}
> 
>-        self.cache_manager = multiprocessing.Manager()
>-        self.stash = serve.stash.StashServer()
>+        mp_context = mpcontext.get_context()
>+        self.cache_manager = mp_context.Manager()
>+        self.stash = serve.stash.StashServer(mp_context=mp_context)
>         self.env_extras = env_extras
>         self.env_extras_cms = None
>         self.ssl_config = ssl_config
>@@ -75,6 +108,7 @@ class TestEnvironment(object):
>         self.mojojs_path = mojojs_path
> 
>     def __enter__(self):
>+        server_log_handler = self.server_logging_ctx.__enter__()
>         self.config_ctx = self.build_config()
> 
>         self.config = self.config_ctx.__enter__()
>@@ -82,8 +116,6 @@ class TestEnvironment(object):
>         self.stash.__enter__()
>         self.cache_manager.__enter__()
> 
>-        self.setup_server_logging()
>-
>         assert self.env_extras_cms is None, (
>             "A TestEnvironment object cannot be nested")
> 
>@@ -94,8 +126,11 @@ class TestEnvironment(object):
>             cm.__enter__()
>             self.env_extras_cms.append(cm)
> 
>-        self.servers = serve.start(self.config,
>-                                   self.get_routes())
>+        self.servers = serve.start(self.server_logger,
>+                                   self.config,
>+                                   self.get_routes(),
>+                                   mp_context=mpcontext.get_context(),
>+                                   log_handlers=[server_log_handler])
> 
>         if self.options.get("supports_debugger") and self.debug_info and self.debug_info.interactive:
>             self.ignore_interrupts()
>@@ -104,9 +139,9 @@ class TestEnvironment(object):
>     def __exit__(self, exc_type, exc_val, exc_tb):
>         self.process_interrupts()
> 
>-        for scheme, servers in iteritems(self.servers):
>+        for scheme, servers in self.servers.items():
>             for port, server in servers:
>-                server.kill()
>+                server.stop()
>         for cm in self.env_extras_cms:
>             cm.__exit__(exc_type, exc_val, exc_tb)
> 
>@@ -115,6 +150,7 @@ class TestEnvironment(object):
>         self.cache_manager.__exit__(exc_type, exc_val, exc_tb)
>         self.stash.__exit__()
>         self.config_ctx.__exit__(exc_type, exc_val, exc_tb)
>+        self.server_logging_ctx.__exit__(exc_type, exc_val, exc_tb)
> 
>     def ignore_interrupts(self):
>         signal.signal(signal.SIGINT, signal.SIG_IGN)
>@@ -125,11 +161,15 @@ class TestEnvironment(object):
>     def build_config(self):
>         override_path = os.path.join(serve_path(self.test_paths), "config.json")
> 
>-        config = serve.ConfigBuilder()
>+        config = serve.ConfigBuilder(self.server_logger)
> 
>         ports = {
>             "http": [8000, 8001],
>+            "http-private": [8002],
>+            "http-public": [8003],
>             "https": [8443, 8444],
>+            "https-private": [8445],
>+            "https-public": [8446],
>             "ws": [8888],
>             "wss": [8889],
>             "h2": [9000],
>@@ -160,24 +200,6 @@ class TestEnvironment(object):
> 
>         return config
> 
>-    def setup_server_logging(self):
>-        server_logger = get_default_logger(component="wptserve")
>-        assert server_logger is not None
>-        log_filter = handlers.LogLevelFilter(lambda x: x, "info")
>-        # Downgrade errors to warnings for the server
>-        log_filter = LogLevelRewriter(log_filter, ["error"], "warning")
>-        server_logger.component_filter = log_filter
>-
>-        server_logger = proxy.QueuedProxyLogger(server_logger)
>-
>-        try:
>-            # Set as the default logger for wptserve
>-            serve.set_logger(server_logger)
>-            serve.logger = server_logger
>-        except Exception:
>-            # This happens if logging has already been set up for wptserve
>-            pass
>-
>     def get_routes(self):
>         route_builder = serve.RoutesBuilder()
> 
>@@ -191,7 +213,8 @@ class TestEnvironment(object):
>                 (self.options.get("testharnessreport", "testharnessreport.js"),
>                  {"output": self.pause_after_test,
>                   "timeout_multiplier": self.testharness_timeout_multipler,
>-                  "explicit_timeout": "true" if self.debug_info is not None else "false"},
>+                  "explicit_timeout": "true" if self.debug_info is not None else "false",
>+                  "debug": "true" if self.debug_test else "false"},
>                  "text/javascript;charset=utf8",
>                  "/resources/testharnessreport.js")]:
>             path = os.path.normpath(os.path.join(here, path))
>@@ -209,7 +232,7 @@ class TestEnvironment(object):
>         route_builder.add_handler("GET", "/resources/testdriver.js",
>                                   StringHandler(data, "text/javascript"))
> 
>-        for url_base, paths in iteritems(self.test_paths):
>+        for url_base, paths in self.test_paths.items():
>             if url_base == "/":
>                 continue
>             route_builder.add_mount_point(url_base, paths["tests_path"])
>@@ -241,13 +264,13 @@ class TestEnvironment(object):
>         failed = []
>         pending = []
>         host = self.config["server_host"]
>-        for scheme, servers in iteritems(self.servers):
>+        for scheme, servers in self.servers.items():
>             for port, server in servers:
>                 if not server.is_alive():
>                     failed.append((scheme, port))
> 
>         if not failed and self.test_server_port:
>-            for scheme, servers in iteritems(self.servers):
>+            for scheme, servers in self.servers.items():
>                 # TODO(Hexcles): Find a way to test QUIC's UDP port.
>                 if scheme == "quic-transport":
>                     continue
>@@ -256,7 +279,7 @@ class TestEnvironment(object):
>                     s.settimeout(0.1)
>                     try:
>                         s.connect((host, port))
>-                    except socket.error:
>+                    except OSError:
>                         pending.append((host, port))
>                     finally:
>                         s.close()
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/actions.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/actions.py
>index b11d30bb94aa..963ed337fde4 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/actions.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/actions.py
>@@ -13,6 +13,18 @@ class ClickAction(object):
>         self.protocol.click.element(element)
> 
> 
>+class DeleteAllCookiesAction(object):
>+    name = "delete_all_cookies"
>+
>+    def __init__(self, logger, protocol):
>+        self.logger = logger
>+        self.protocol = protocol
>+
>+    def __call__(self, payload):
>+        self.logger.debug("Deleting all cookies")
>+        self.protocol.cookies.delete_all_cookies()
>+
>+
> class SendKeysAction(object):
>     name = "send_keys"
> 
>@@ -171,6 +183,7 @@ class SetUserVerifiedAction(object):
> 
> 
> actions = [ClickAction,
>+           DeleteAllCookiesAction,
>            SendKeysAction,
>            ActionSequenceAction,
>            GenerateTestReportAction,
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/base.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/base.py
>index 4c3891c1cb67..a88ab82e78d3 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/base.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/base.py
>@@ -8,29 +8,30 @@ import traceback
> import socket
> import sys
> from abc import ABCMeta, abstractmethod
>-from six import text_type
>-from six.moves.http_client import HTTPConnection
>-from six.moves.urllib.parse import urljoin, urlsplit, urlunsplit
>+from http.client import HTTPConnection
>+from typing import Any, Callable, ClassVar, Optional, Tuple, Type, TYPE_CHECKING
>+from urllib.parse import urljoin, urlsplit, urlunsplit
> 
>-from ..testrunner import Stop
> from .actions import actions
> from .protocol import Protocol, BaseProtocolPart
> 
>+if TYPE_CHECKING:
>+    from ..webdriver_server import WebDriverServer
>+
> here = os.path.dirname(__file__)
> 
> 
>-def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>-                    **kwargs):
>+def executor_kwargs(test_type, test_environment, run_info_data, **kwargs):
>     timeout_multiplier = kwargs["timeout_multiplier"]
>     if timeout_multiplier is None:
>         timeout_multiplier = 1
> 
>-    executor_kwargs = {"server_config": server_config,
>+    executor_kwargs = {"server_config": test_environment.config,
>                        "timeout_multiplier": timeout_multiplier,
>                        "debug_info": kwargs["debug_info"]}
> 
>     if test_type in ("reftest", "print-reftest"):
>-        executor_kwargs["screenshot_cache"] = cache_manager.dict()
>+        executor_kwargs["screenshot_cache"] = test_environment.cache_manager.dict()
> 
>     if test_type == "wdspec":
>         executor_kwargs["binary"] = kwargs.get("binary")
>@@ -42,7 +43,7 @@ def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
>     # want to view the results, however, the executor has to skip that cleanup.
>     if kwargs["pause_after_test"] or kwargs["pause_on_unexpected"]:
>         executor_kwargs["cleanup_after_test"] = False
>-
>+    executor_kwargs["debug_test"] = kwargs["debug_test"]
>     return executor_kwargs
> 
> 
>@@ -180,11 +181,11 @@ class TimedRunner(object):
>         self.result_flag = threading.Event()
> 
>     def run(self):
>-        if self.set_timeout() is Stop:
>-            return Stop
>-
>-        if self.before_run() is Stop:
>-            return Stop
>+        for setup_fn in [self.set_timeout, self.before_run]:
>+            err = setup_fn()
>+            if err:
>+                self.result = (False, err)
>+                return self.result
> 
>         executor = threading.Thread(target=self.run_func)
>         executor.start()
>@@ -243,8 +244,14 @@ class TestExecutor(object):
>     """
>     __metaclass__ = ABCMeta
> 
>-    test_type = None
>-    convert_result = None
>+    test_type = None  # type: ClassVar[str]
>+    # convert_result is a class variable set to a callable converter
>+    # (e.g. reftest_result_converter) converting from an instance of
>+    # URLManifestItem (e.g. RefTest) + type-dependent results object +
>+    # type-dependent extra data, returning a tuple of Result and list of
>+    # SubtestResult. For now, any callable is accepted. TODO: Make this type
>+    # stricter when more of the surrounding code is annotated.
>+    convert_result = None  # type: ClassVar[Callable[..., Any]]
>     supports_testdriver = False
>     supports_jsshell = False
>     # Extra timeout to use after internal test timeout at which the harness
>@@ -287,18 +294,15 @@ class TestExecutor(object):
>         """Run a particular test.
> 
>         :param test: The test to run"""
>-        if test.environment != self.last_environment:
>-            self.on_environment_change(test.environment)
>         try:
>+            if test.environment != self.last_environment:
>+                self.on_environment_change(test.environment)
>             result = self.do_test(test)
>         except Exception as e:
>             exception_string = traceback.format_exc()
>             self.logger.warning(exception_string)
>             result = self.result_from_exception(test, e, exception_string)
> 
>-        if result is Stop:
>-            return result
>-
>         # log result of parent test
>         if result[0].status == "ERROR":
>             self.logger.debug(result[0].message)
>@@ -307,14 +311,18 @@ class TestExecutor(object):
> 
>         self.runner.send_message("test_ended", test, result)
> 
>-    def server_url(self, protocol):
>+    def server_url(self, protocol, subdomain=False):
>         scheme = "https" if protocol == "h2" else protocol
>-        return "%s://%s:%s" % (scheme,
>-                               self.server_config["browser_host"],
>-                               self.server_config["ports"][protocol][0])
>+        host = self.server_config["browser_host"]
>+        if subdomain:
>+            # The only supported subdomain filename flag is "www".
>+            host = "{subdomain}.{host}".format(subdomain="www", host=host)
>+        return "{scheme}://{host}:{port}".format(scheme=scheme, host=host,
>+            port=self.server_config["ports"][protocol][0])
> 
>     def test_url(self, test):
>-        return urljoin(self.server_url(test.environment["protocol"]), test.url)
>+        return urljoin(self.server_url(test.environment["protocol"],
>+                                       test.subdomain), test.url)
> 
>     @abstractmethod
>     def do_test(self, test):
>@@ -332,7 +340,7 @@ class TestExecutor(object):
>             status = e.status
>         else:
>             status = "INTERNAL-ERROR"
>-        message = text_type(getattr(e, "message", ""))
>+        message = str(getattr(e, "message", ""))
>         if message:
>             message += "\n"
>         message += exception_string
>@@ -423,7 +431,7 @@ class RefTestImplementation(object):
> 
>         if len(lhs_hashes) != len(rhs_hashes):
>             self.logger.info("Got different number of pages")
>-            return False
>+            return relation == "!=", None
> 
>         assert len(lhs_screenshots) == len(lhs_hashes) == len(rhs_screenshots) == len(rhs_hashes)
> 
>@@ -590,11 +598,11 @@ class RefTestImplementation(object):
> 
> class WdspecExecutor(TestExecutor):
>     convert_result = pytest_result_converter
>-    protocol_cls = None
>+    protocol_cls = None  # type: ClassVar[Type[Protocol]]
> 
>     def __init__(self, logger, browser, server_config, webdriver_binary,
>                  webdriver_args, timeout_multiplier=1, capabilities=None,
>-                 debug_info=None, **kwargs):
>+                 debug_info=None, environ=None, **kwargs):
>         self.do_delayed_imports()
>         TestExecutor.__init__(self, logger, browser, server_config,
>                               timeout_multiplier=timeout_multiplier,
>@@ -603,7 +611,13 @@ class WdspecExecutor(TestExecutor):
>         self.webdriver_args = webdriver_args
>         self.timeout_multiplier = timeout_multiplier
>         self.capabilities = capabilities
>-        self.protocol = self.protocol_cls(self, browser)
>+        self.environ = environ if environ is not None else {}
>+        self.output_handler_kwargs = None
>+        self.output_handler_start_kwargs = None
>+
>+    def setup(self, runner):
>+        self.protocol = self.protocol_cls(self, self.browser)
>+        super().setup(runner)
> 
>     def is_alive(self):
>         return self.protocol.is_alive()
>@@ -706,7 +720,7 @@ class ConnectionlessProtocol(Protocol):
> 
> 
> class WdspecProtocol(Protocol):
>-    server_cls = None
>+    server_cls = None  # type: ClassVar[Optional[Type[WebDriverServer]]]
> 
>     implements = [ConnectionlessBaseProtocolPart]
> 
>@@ -717,14 +731,21 @@ class WdspecProtocol(Protocol):
>         self.capabilities = self.executor.capabilities
>         self.session_config = None
>         self.server = None
>+        self.environ = os.environ.copy()
>+        self.environ.update(executor.environ)
>+        self.output_handler_kwargs = executor.output_handler_kwargs
>+        self.output_handler_start_kwargs = executor.output_handler_start_kwargs
> 
>     def connect(self):
>         """Connect to browser via the HTTP server."""
>         self.server = self.server_cls(
>             self.logger,
>             binary=self.webdriver_binary,
>-            args=self.webdriver_args)
>-        self.server.start(block=False)
>+            args=self.webdriver_args,
>+            env=self.environ)
>+        self.server.start(block=False,
>+                          output_handler_kwargs=self.output_handler_kwargs,
>+                          output_handler_start_kwargs=self.output_handler_start_kwargs)
>         self.logger.info(
>             "WebDriver HTTP server listening at %s" % self.server.url)
>         self.session_config = {"host": self.server.host,
>@@ -762,7 +783,7 @@ class CallbackHandler(object):
>     WebDriver. Things that are more different to WebDriver may need to create a
>     fully custom implementation."""
> 
>-    unimplemented_exc = (NotImplementedError,)
>+    unimplemented_exc = (NotImplementedError,)  # type: ClassVar[Tuple[Type[Exception], ...]]
> 
>     def __init__(self, logger, protocol, test_window):
>         self.protocol = protocol
>@@ -831,7 +852,7 @@ class ActionContext(object):
> 
>         self.initial_window = self.protocol.base.current_window
>         self.logger.debug("Switching to window %s" % self.context)
>-        self.protocol.testdriver.switch_to_window(self.context)
>+        self.protocol.testdriver.switch_to_window(self.context, self.initial_window)
> 
>     def __exit__(self, *args):
>         if self.context is None:
>@@ -839,5 +860,4 @@ class ActionContext(object):
> 
>         self.logger.debug("Switching back to initial window")
>         self.protocol.base.set_window(self.initial_window)
>-        self.protocol.testdriver._switch_to_frame(None)
>         self.initial_window = None
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorchrome.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorchrome.py
>index 3a704754137f..431d398ebd27 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorchrome.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorchrome.py
>@@ -1,7 +1,7 @@
> import os
> import traceback
> 
>-from six.moves.urllib.parse import urljoin
>+from urllib.parse import urljoin
> 
> from .base import WdspecProtocol, WdspecExecutor, get_pages
> from .executorwebdriver import WebDriverProtocol, WebDriverRefTestExecutor, WebDriverRun
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executormarionette.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executormarionette.py
>index 7e2cc8e38a44..25a3360b7d80 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executormarionette.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executormarionette.py
>@@ -5,8 +5,7 @@ import time
> import traceback
> import uuid
> 
>-from six import iteritems, iterkeys
>-from six.moves.urllib.parse import urljoin
>+from urllib.parse import urljoin
> 
> errors = None
> marionette = None
>@@ -33,27 +32,22 @@ from .protocol import (ActionSequenceProtocolPart,
>                        StorageProtocolPart,
>                        SelectorProtocolPart,
>                        ClickProtocolPart,
>+                       CookiesProtocolPart,
>                        SendKeysProtocolPart,
>                        TestDriverProtocolPart,
>                        CoverageProtocolPart,
>                        GenerateTestReportProtocolPart,
>                        VirtualAuthenticatorProtocolPart,
>                        SetPermissionProtocolPart,
>-                       PrintProtocolPart)
>-from ..testrunner import Stop
>-from ..webdriver_server import GeckoDriverServer
>+                       PrintProtocolPart,
>+                       DebugProtocolPart)
> 
> 
> def do_delayed_imports():
>-    global errors, marionette
>+    global errors, marionette, Addons
> 
>-    # Marionette client used to be called marionette, recently it changed
>-    # to marionette_driver for unfathomable reasons
>-    try:
>-        import marionette
>-        from marionette import errors
>-    except ImportError:
>-        from marionette_driver import marionette, errors
>+    from marionette_driver import marionette, errors
>+    from marionette_driver.addons import Addons
> 
> 
> def _switch_to_window(marionette, handle):
>@@ -133,7 +127,7 @@ class MarionetteBaseProtocolPart(BaseProtocolPart):
>                 pass
>             except errors.JavascriptException as e:
>                 # This can happen if we navigate, but just keep going
>-                self.logger.debug(e.message)
>+                self.logger.debug(e)
>                 pass
>             except IOError:
>                 self.logger.debug("Socket closed")
>@@ -441,6 +435,15 @@ class MarionetteClickProtocolPart(ClickProtocolPart):
>         return element.click()
> 
> 
>+class MarionetteCookiesProtocolPart(CookiesProtocolPart):
>+    def setup(self):
>+        self.marionette = self.parent.marionette
>+
>+    def delete_all_cookies(self):
>+        self.logger.info("Deleting all cookies")
>+        return self.marionette.delete_all_cookies()
>+
>+
> class MarionetteSendKeysProtocolPart(SendKeysProtocolPart):
>     def setup(self):
>         self.marionette = self.parent.marionette
>@@ -473,8 +476,12 @@ class MarionetteTestDriverProtocolPart(TestDriverProtocolPart):
>             obj["message"] = str(message)
>         self.parent.base.execute_script("window.postMessage(%s, '*')" % json.dumps(obj))
> 
>-    def _switch_to_frame(self, frame_number):
>-        self.marionette.switch_to_frame(frame_number)
>+    def _switch_to_frame(self, index_or_elem):
>+        try:
>+            self.marionette.switch_to_frame(index_or_elem)
>+        except (errors.NoSuchFrameException,
>+                errors.StaleElementException) as e:
>+            raise ValueError from e
> 
>     def _switch_to_parent_frame(self):
>         self.marionette.switch_to_parent_frame()
>@@ -489,7 +496,7 @@ class MarionetteCoverageProtocolPart(CoverageProtocolPart):
>             return
> 
>         script = """
>-            const {PerTestCoverageUtils} = ChromeUtils.import("chrome://marionette/content/PerTestCoverageUtils.jsm");
>+            const {PerTestCoverageUtils} = ChromeUtils.import("chrome://remote/content/marionette/PerTestCoverageUtils.jsm");
>             return PerTestCoverageUtils.enabled;
>             """
>         with self.marionette.using_context(self.marionette.CONTEXT_CHROME):
>@@ -499,7 +506,7 @@ class MarionetteCoverageProtocolPart(CoverageProtocolPart):
>         script = """
>             var callback = arguments[arguments.length - 1];
> 
>-            const {PerTestCoverageUtils} = ChromeUtils.import("chrome://marionette/content/PerTestCoverageUtils.jsm");
>+            const {PerTestCoverageUtils} = ChromeUtils.import("chrome://remote/content/marionette/PerTestCoverageUtils.jsm");
>             PerTestCoverageUtils.beforeTest().then(callback, callback);
>             """
>         with self.marionette.using_context(self.marionette.CONTEXT_CHROME):
>@@ -519,7 +526,7 @@ class MarionetteCoverageProtocolPart(CoverageProtocolPart):
>         script = """
>             var callback = arguments[arguments.length - 1];
> 
>-            const {PerTestCoverageUtils} = ChromeUtils.import("chrome://marionette/content/PerTestCoverageUtils.jsm");
>+            const {PerTestCoverageUtils} = ChromeUtils.import("chrome://remote/content/marionette/PerTestCoverageUtils.jsm");
>             PerTestCoverageUtils.afterTest().then(callback, callback);
>             """
>         with self.marionette.using_context(self.marionette.CONTEXT_CHROME):
>@@ -563,12 +570,22 @@ class MarionetteVirtualAuthenticatorProtocolPart(VirtualAuthenticatorProtocolPar
>     def set_user_verified(self, authenticator_id, uv):
>         raise NotImplementedError("set_user_verified not yet implemented")
> 
>+
> class MarionetteSetPermissionProtocolPart(SetPermissionProtocolPart):
>     def setup(self):
>         self.marionette = self.parent.marionette
> 
>-    def set_permission(self, name, state, one_realm):
>-        raise NotImplementedError("set_permission not yet implemented")
>+    def set_permission(self, descriptor, state, one_realm):
>+        body = {
>+            "descriptor": descriptor,
>+            "state": state,
>+        }
>+        if one_realm is not None:
>+            body["oneRealm"] = one_realm
>+        try:
>+            self.marionette._send_message("WebDriver:SetPermission", body)
>+        except errors.UnsupportedOperationException:
>+            raise NotImplementedError("set_permission not yet implemented")
> 
> 
> class MarionettePrintProtocolPart(PrintProtocolPart):
>@@ -621,6 +638,30 @@ render('%s').then(result => callback(result))""" % pdf_base64, new_sandbox=False
>         finally:
>             _switch_to_window(self.marionette, handle)
> 
>+
>+class MarionetteDebugProtocolPart(DebugProtocolPart):
>+    def setup(self):
>+        self.marionette = self.parent.marionette
>+
>+    def load_devtools(self):
>+        with self.marionette.using_context(self.marionette.CONTEXT_CHROME):
>+            self.parent.base.execute_script("""
>+const { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm");
>+const { TargetFactory } = require("devtools/client/framework/target");
>+const { gDevTools } = require("devtools/client/framework/devtools");
>+
>+const callback = arguments[arguments.length - 1];
>+
>+async function loadDevTools() {
>+    const target = await TargetFactory.forTab(window.gBrowser.selectedTab);
>+    await gDevTools.showToolbox(target, "webconsole", "window");
>+}
>+
>+loadDevTools().catch(() => dump("Devtools failed to load"))
>+              .then(callback);
>+""", asynchronous=True)
>+
>+
> class MarionetteProtocol(Protocol):
>     implements = [MarionetteBaseProtocolPart,
>                   MarionetteTestharnessProtocolPart,
>@@ -628,6 +669,7 @@ class MarionetteProtocol(Protocol):
>                   MarionetteStorageProtocolPart,
>                   MarionetteSelectorProtocolPart,
>                   MarionetteClickProtocolPart,
>+                  MarionetteCookiesProtocolPart,
>                   MarionetteSendKeysProtocolPart,
>                   MarionetteActionSequenceProtocolPart,
>                   MarionetteTestDriverProtocolPart,
>@@ -636,7 +678,8 @@ class MarionetteProtocol(Protocol):
>                   MarionetteGenerateTestReportProtocolPart,
>                   MarionetteVirtualAuthenticatorProtocolPart,
>                   MarionetteSetPermissionProtocolPart,
>-                  MarionettePrintProtocolPart]
>+                  MarionettePrintProtocolPart,
>+                  MarionetteDebugProtocolPart]
> 
>     def __init__(self, executor, browser, capabilities=None, timeout_multiplier=1, e10s=True, ccov=False):
>         do_delayed_imports()
>@@ -680,11 +723,12 @@ class MarionetteProtocol(Protocol):
>             try:
>                 self.marionette._request_in_app_shutdown()
>                 self.marionette.delete_session(send_request=False)
>+                self.marionette.cleanup()
>             except Exception:
>                 # This is typically because the session never started
>                 pass
>         if self.marionette is not None:
>-            del self.marionette
>+            self.marionette = None
>         super(MarionetteProtocol, self).teardown()
> 
>     def is_alive(self):
>@@ -696,20 +740,19 @@ class MarionetteProtocol(Protocol):
> 
>     def on_environment_change(self, old_environment, new_environment):
>         #Unset all the old prefs
>-        for name in iterkeys(old_environment.get("prefs", {})):
>+        for name in old_environment.get("prefs", {}).keys():
>             value = self.executor.original_pref_values[name]
>             if value is None:
>                 self.prefs.clear(name)
>             else:
>                 self.prefs.set(name, value)
> 
>-        for name, value in iteritems(new_environment.get("prefs", {})):
>+        for name, value in new_environment.get("prefs", {}).items():
>             self.executor.original_pref_values[name] = self.prefs.get(name)
>             self.prefs.set(name, value)
> 
> 
> class ExecuteAsyncScriptRun(TimedRunner):
>-
>     def set_timeout(self):
>         timeout = self.timeout
> 
>@@ -722,8 +765,9 @@ class ExecuteAsyncScriptRun(TimedRunner):
>                 # timeout is set too high. This works at least.
>                 self.protocol.base.set_timeout(2**28 - 1)
>         except IOError:
>-            self.logger.error("Lost marionette connection before starting test")
>-            return Stop
>+            msg = "Lost marionette connection before starting test"
>+            self.logger.error(msg)
>+            return ("INTERNAL-ERROR", msg)
> 
>     def before_run(self):
>         index = self.url.rfind("/storage/")
>@@ -747,7 +791,7 @@ class ExecuteAsyncScriptRun(TimedRunner):
>             self.logger.info("NoSuchWindowException on command, setting status to CRASH")
>             self.result = False, ("CRASH", None)
>         except Exception as e:
>-            if isinstance(e, errors.JavascriptException) and e.message.startswith("Document was unloaded"):
>+            if isinstance(e, errors.JavascriptException) and str(e).startswith("Document was unloaded"):
>                 message = "Document unloaded; maybe test navigated the top-level-browsing context?"
>             else:
>                 message = getattr(e, "message", "")
>@@ -765,7 +809,7 @@ class MarionetteTestharnessExecutor(TestharnessExecutor):
> 
>     def __init__(self, logger, browser, server_config, timeout_multiplier=1,
>                  close_after_done=True, debug_info=None, capabilities=None,
>-                 debug=False, ccov=False, **kwargs):
>+                 debug=False, ccov=False, debug_test=False, **kwargs):
>         """Marionette-based executor for testharness.js tests"""
>         TestharnessExecutor.__init__(self, logger, browser, server_config,
>                                      timeout_multiplier=timeout_multiplier,
>@@ -781,6 +825,9 @@ class MarionetteTestharnessExecutor(TestharnessExecutor):
>         self.close_after_done = close_after_done
>         self.window_id = str(uuid.uuid4())
>         self.debug = debug
>+        self.debug_test = debug_test
>+
>+        self.install_extensions = browser.extensions
> 
>         self.original_pref_values = {}
> 
>@@ -789,6 +836,11 @@ class MarionetteTestharnessExecutor(TestharnessExecutor):
> 
>     def setup(self, runner):
>         super(MarionetteTestharnessExecutor, self).setup(runner)
>+        for extension_path in self.install_extensions:
>+            self.logger.info("Installing extension from %s" % extension_path)
>+            addons = Addons(self.protocol.marionette)
>+            addons.install(extension_path)
>+
>         self.protocol.testharness.load_runner(self.last_environment["protocol"])
> 
>     def is_alive(self):
>@@ -842,6 +894,9 @@ class MarionetteTestharnessExecutor(TestharnessExecutor):
>         self.protocol.base.set_window(test_window)
>         protocol.testharness.test_window_loaded()
> 
>+        if self.debug_test:
>+            self.protocol.debug.load_devtools()
>+
>         handler = CallbackHandler(self.logger, protocol, test_window)
>         protocol.marionette.navigate(url)
>         while True:
>@@ -868,7 +923,7 @@ class MarionetteRefTestExecutor(RefTestExecutor):
>                  debug_info=None, reftest_internal=False,
>                  reftest_screenshot="unexpected", ccov=False,
>                  group_metadata=None, capabilities=None, debug=False,
>-                 browser_version=None, **kwargs):
>+                 browser_version=None, debug_test=False, **kwargs):
>         """Marionette-based executor for reftests"""
>         RefTestExecutor.__init__(self,
>                                  logger,
>@@ -891,6 +946,7 @@ class MarionetteRefTestExecutor(RefTestExecutor):
>         self.original_pref_values = {}
>         self.group_metadata = group_metadata
>         self.debug = debug
>+        self.debug_test = debug_test
> 
>         with open(os.path.join(here, "reftest.js")) as f:
>             self.script = f.read()
>@@ -953,7 +1009,12 @@ class MarionetteRefTestExecutor(RefTestExecutor):
>             assertion_count = self.protocol.asserts.get()
>             if "extra" not in result:
>                 result["extra"] = {}
>-            result["extra"]["assertion_count"] = assertion_count
>+            if assertion_count is not None:
>+                result["extra"]["assertion_count"] = assertion_count
>+
>+        if self.debug_test and result["status"] in ["PASS", "FAIL", "ERROR"] and "extra" in result:
>+            self.protocol.base.set_window(self.protocol.base.window_handles()[0])
>+            self.protocol.debug.load_reftest_analyzer(test, result)
> 
>         return self.convert_result(test, result)
> 
>@@ -1000,8 +1061,7 @@ class InternalRefTestImplementation(RefTestImplementation):
>         data = {"screenshot": screenshot, "isPrint": self.executor.is_print}
>         if self.executor.group_metadata is not None:
>             data["urlCount"] = {urljoin(self.executor.server_url(key[0]), key[1]):value
>-                                for key, value in iteritems(
>-                                    self.executor.group_metadata.get("url_count", {}))
>+                                for key, value in self.executor.group_metadata.get("url_count", {}).items()
>                                 if value > 1}
>         self.chrome_scope = chrome_scope
>         if chrome_scope:
>@@ -1053,12 +1113,32 @@ class InternalRefTestImplementation(RefTestImplementation):
> 
> 
> class GeckoDriverProtocol(WdspecProtocol):
>-    server_cls = GeckoDriverServer
>+    server_cls = None  # To avoid circular imports we set this at runtime
> 
> 
> class MarionetteWdspecExecutor(WdspecExecutor):
>     protocol_cls = GeckoDriverProtocol
> 
>+    def __init__(self, logger, browser, server_config, webdriver_binary,
>+                 webdriver_args, timeout_multiplier=1, capabilities=None,
>+                 debug_info=None, environ=None, stackfix_dir=None,
>+                 symbols_path=None, leak_report_file=None, asan=False,
>+                 group_metadata=None, browser_settings=None, **kwargs):
>+
>+        from ..browsers.firefox import GeckoDriverServer
>+        super().__init__(logger, browser, server_config, webdriver_binary,
>+                         webdriver_args, timeout_multiplier=timeout_multiplier,
>+                         capabilities=capabilities, debug_info=debug_info,
>+                         environ=environ, **kwargs)
>+        self.protocol_cls.server_cls = GeckoDriverServer
>+        self.output_handler_kwargs = {"stackfix_dir": stackfix_dir,
>+                                      "symbols_path": symbols_path,
>+                                      "asan": asan,
>+                                      "leak_report_file": leak_report_file}
>+        self.output_handler_start_kwargs = {"group_metadata": group_metadata}
>+        self.output_handler_start_kwargs.update(browser_settings)
>+
>+
> 
> class MarionetteCrashtestExecutor(CrashtestExecutor):
>     def __init__(self, logger, browser, server_config, timeout_multiplier=1,
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorselenium.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorselenium.py
>index ff26351f84ed..9d675cb3ef87 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorselenium.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorselenium.py
>@@ -1,4 +1,3 @@
>-from __future__ import absolute_import
> import json
> import os
> import socket
>@@ -6,7 +5,7 @@ import threading
> import time
> import traceback
> import uuid
>-from six.moves.urllib.parse import urljoin
>+from urllib.parse import urljoin
> 
> from .base import (CallbackHandler,
>                    RefTestExecutor,
>@@ -19,10 +18,10 @@ from .protocol import (BaseProtocolPart,
>                        Protocol,
>                        SelectorProtocolPart,
>                        ClickProtocolPart,
>+                       CookiesProtocolPart,
>                        SendKeysProtocolPart,
>                        ActionSequenceProtocolPart,
>                        TestDriverProtocolPart)
>-from ..testrunner import Stop
> 
> here = os.path.dirname(__file__)
> 
>@@ -183,6 +182,15 @@ class SeleniumClickProtocolPart(ClickProtocolPart):
>         return element.click()
> 
> 
>+class SeleniumCookiesProtocolPart(CookiesProtocolPart):
>+    def setup(self):
>+        self.webdriver = self.parent.webdriver
>+
>+    def delete_all_cookies(self):
>+        self.logger.info("Deleting all cookies")
>+        return self.webdriver.delete_all_cookies()
>+
>+
> class SeleniumSendKeysProtocolPart(SendKeysProtocolPart):
>     def setup(self):
>         self.webdriver = self.parent.webdriver
>@@ -219,6 +227,7 @@ class SeleniumProtocol(Protocol):
>                   SeleniumTestharnessProtocolPart,
>                   SeleniumSelectorProtocolPart,
>                   SeleniumClickProtocolPart,
>+                  SeleniumCookiesProtocolPart,
>                   SeleniumSendKeysProtocolPart,
>                   SeleniumTestDriverProtocolPart,
>                   SeleniumActionSequenceProtocolPart]
>@@ -267,8 +276,9 @@ class SeleniumRun(TimedRunner):
>         try:
>             self.protocol.base.set_timeout(timeout + self.extra_timeout)
>         except exceptions.ErrorInResponseException:
>-            self.logger.error("Lost WebDriver connection")
>-            return Stop
>+            msg = "Lost WebDriver connection"
>+            self.logger.error(msg)
>+            return ("INTERNAL-ERROR", msg)
> 
>     def run_func(self):
>         try:
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorservo.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorservo.py
>index efe93abc69c7..f322421bd3fa 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorservo.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorservo.py
>@@ -1,4 +1,3 @@
>-from __future__ import print_function
> import base64
> import json
> import os
>@@ -7,7 +6,6 @@ import tempfile
> import threading
> import traceback
> import uuid
>-from six import ensure_str, iteritems
> 
> from mozprocess import ProcessHandler
> 
>@@ -23,7 +21,6 @@ from .base import (ConnectionlessProtocol,
>                    WdspecProtocol)
> from .process import ProcessTestExecutor
> from ..browsers.base import browser_command
>-from ..process import cast_env
> from ..webdriver_server import ServoDriverServer
> 
> 
>@@ -48,7 +45,7 @@ def build_servo_command(test, test_url_func, browser, binary, pause_after_test,
>         args += ["-Z", debug_opts]
>     for stylesheet in browser.user_stylesheets:
>         args += ["--user-stylesheet", stylesheet]
>-    for pref, value in iteritems(test.environment.get('prefs', {})):
>+    for pref, value in test.environment.get('prefs', {}).items():
>         args += ["--pref", "%s=%s" % (pref, value)]
>     if browser.ca_certificate_path:
>         args += ["--certificate-path", browser.ca_certificate_path]
>@@ -103,11 +100,11 @@ class ServoTestharnessExecutor(ProcessTestExecutor):
>             self.proc = ProcessHandler(self.command,
>                                        processOutputLine=[self.on_output],
>                                        onFinish=self.on_finish,
>-                                       env=cast_env(env),
>+                                       env=env,
>                                        storeOutput=False)
>             self.proc.run()
>         else:
>-            self.proc = subprocess.Popen(self.command, env=cast_env(env))
>+            self.proc = subprocess.Popen(self.command, env=env)
> 
>         try:
>             timeout = test.timeout * self.timeout_multiplier
>@@ -235,7 +232,7 @@ class ServoRefTestExecutor(ProcessTestExecutor):
>             if not self.interactive:
>                 self.proc = ProcessHandler(self.command,
>                                            processOutputLine=[self.on_output],
>-                                           env=cast_env(env))
>+                                           env=env)
> 
> 
>                 try:
>@@ -247,7 +244,7 @@ class ServoRefTestExecutor(ProcessTestExecutor):
>                     raise
>             else:
>                 self.proc = subprocess.Popen(self.command,
>-                                             env=cast_env(env))
>+                                             env=env)
>                 try:
>                     rv = self.proc.wait()
>                 except KeyboardInterrupt:
>@@ -264,7 +261,9 @@ class ServoRefTestExecutor(ProcessTestExecutor):
>             with open(output_path, "rb") as f:
>                 # Might need to strip variable headers or something here
>                 data = f.read()
>-                return True, [ensure_str(base64.b64encode(data))]
>+                # Returning the screenshot as a string could potentially be avoided,
>+                # see https://github.com/web-platform-tests/wpt/issues/28929.
>+                return True, [base64.b64encode(data).decode()]
> 
>     def do_test(self, test):
>         result = self.implementation.run_test(test)
>@@ -357,11 +356,11 @@ class ServoCrashtestExecutor(ProcessTestExecutor):
> 
>         if not self.interactive:
>             self.proc = ProcessHandler(command,
>-                                       env=cast_env(env),
>+                                       env=env,
>                                        storeOutput=False)
>             self.proc.run()
>         else:
>-            self.proc = subprocess.Popen(command, env=cast_env(env))
>+            self.proc = subprocess.Popen(command, env=env)
> 
>         self.proc.wait()
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorservodriver.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorservodriver.py
>index 2cd1dbf3ad06..039bcd14e2be 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorservodriver.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorservodriver.py
>@@ -10,7 +10,6 @@ from .base import (Protocol,
>                    TestharnessExecutor,
>                    TimedRunner,
>                    strip_server)
>-from ..testrunner import Stop
> from ..webdriver_server import wait_for_service
> 
> webdriver = None
>@@ -184,8 +183,9 @@ class ServoWebDriverTestharnessExecutor(TestharnessExecutor):
>                 self.protocol.session.timeouts.script = timeout
>                 self.timeout = timeout
>             except IOError:
>-                self.logger.error("Lost webdriver connection")
>-                return Stop
>+                msg = "Lost WebDriver connection"
>+                self.logger.error(msg)
>+                return ("INTERNAL-ERROR", msg)
> 
>         success, data = ServoWebDriverRun(self.logger,
>                                           self.do_testharness,
>@@ -276,8 +276,9 @@ class ServoWebDriverRefTestExecutor(RefTestExecutor):
>                 self.protocol.session.timeouts.script = timeout
>                 self.timeout = timeout
>             except IOError:
>-                self.logger.error("Lost webdriver connection")
>-                return Stop
>+                msg = "Lost webdriver connection"
>+                self.logger.error(msg)
>+                return ("INTERNAL-ERROR", msg)
> 
>         return ServoWebDriverRun(self.logger,
>                                  self._screenshot,
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorwebdriver.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorwebdriver.py
>index bad5fd072237..6d5916a6afbc 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorwebdriver.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/executorwebdriver.py
>@@ -1,4 +1,3 @@
>-from __future__ import absolute_import
> import json
> import os
> import socket
>@@ -6,7 +5,7 @@ import threading
> import time
> import traceback
> import uuid
>-from six.moves.urllib.parse import urljoin
>+from urllib.parse import urljoin
> 
> from .base import (CallbackHandler,
>                    CrashtestExecutor,
>@@ -20,22 +19,23 @@ from .protocol import (BaseProtocolPart,
>                        Protocol,
>                        SelectorProtocolPart,
>                        ClickProtocolPart,
>+                       CookiesProtocolPart,
>                        SendKeysProtocolPart,
>                        ActionSequenceProtocolPart,
>                        TestDriverProtocolPart,
>                        GenerateTestReportProtocolPart,
>                        SetPermissionProtocolPart,
>-                       VirtualAuthenticatorProtocolPart)
>-from ..testrunner import Stop
>+                       VirtualAuthenticatorProtocolPart,
>+                       DebugProtocolPart)
> 
>-import webdriver as client
>+from webdriver.client import Session
> from webdriver import error
> 
> here = os.path.dirname(__file__)
> 
> 
> class WebDriverCallbackHandler(CallbackHandler):
>-    unimplemented_exc = (NotImplementedError, client.UnknownCommandException)
>+    unimplemented_exc = (NotImplementedError, error.UnknownCommandException)
> 
> 
> class WebDriverBaseProtocolPart(BaseProtocolPart):
>@@ -49,7 +49,7 @@ class WebDriverBaseProtocolPart(BaseProtocolPart):
>     def set_timeout(self, timeout):
>         try:
>             self.webdriver.timeouts.script = timeout
>-        except client.WebDriverException:
>+        except error.WebDriverException:
>             # workaround https://bugs.chromium.org/p/chromedriver/issues/detail?id=2057
>             body = {"type": "script", "ms": timeout * 1000}
>             self.webdriver.send_session_command("POST", "timeouts", body)
>@@ -71,16 +71,16 @@ class WebDriverBaseProtocolPart(BaseProtocolPart):
>         while True:
>             try:
>                 self.webdriver.execute_async_script("")
>-            except (client.TimeoutException,
>-                    client.ScriptTimeoutException,
>-                    client.JavascriptErrorException):
>+            except (error.TimeoutException,
>+                    error.ScriptTimeoutException,
>+                    error.JavascriptErrorException):
>                 # A JavascriptErrorException will happen when we navigate;
>                 # by ignoring it it's possible to reload the test whilst the
>                 # harness remains paused
>                 pass
>             except (socket.timeout,
>-                    client.NoSuchWindowException,
>-                    client.UnknownErrorException,
>+                    error.NoSuchWindowException,
>+                    error.UnknownErrorException,
>                     IOError):
>                 break
>             except Exception:
>@@ -116,7 +116,7 @@ class WebDriverTestharnessProtocolPart(TestharnessProtocolPart):
>             try:
>                 self.webdriver.window_handle = handle
>                 self.webdriver.window.close()
>-            except client.NoSuchWindowException:
>+            except error.NoSuchWindowException:
>                 pass
>         self.webdriver.window_handle = self.runner_handle
>         return self.runner_handle
>@@ -190,6 +190,15 @@ class WebDriverClickProtocolPart(ClickProtocolPart):
>         return element.click()
> 
> 
>+class WebDriverCookiesProtocolPart(CookiesProtocolPart):
>+    def setup(self):
>+        self.webdriver = self.parent.webdriver
>+
>+    def delete_all_cookies(self):
>+        self.logger.info("Deleting all cookies")
>+        return self.webdriver.send_session_command("DELETE", "cookie")
>+
>+
> class WebDriverSendKeysProtocolPart(SendKeysProtocolPart):
>     def setup(self):
>         self.webdriver = self.parent.webdriver
>@@ -197,7 +206,7 @@ class WebDriverSendKeysProtocolPart(SendKeysProtocolPart):
>     def send_keys(self, element, keys):
>         try:
>             return element.send_keys(keys)
>-        except client.UnknownErrorException as e:
>+        except error.UnknownErrorException as e:
>             # workaround https://bugs.chromium.org/p/chromedriver/issues/detail?id=1999
>             if (e.http_status != 500 or
>                 e.status_code != "unknown error"):
>@@ -227,8 +236,12 @@ class WebDriverTestDriverProtocolPart(TestDriverProtocolPart):
>             obj["message"] = str(message)
>         self.webdriver.execute_script("window.postMessage(%s, '*')" % json.dumps(obj))
> 
>-    def _switch_to_frame(self, frame_number):
>-        self.webdriver.switch_frame(frame_number)
>+    def _switch_to_frame(self, index_or_elem):
>+        try:
>+            self.webdriver.switch_frame(index_or_elem)
>+        except (error.StaleElementReferenceException,
>+                error.NoSuchFrameException) as e:
>+            raise ValueError from e
> 
>     def _switch_to_parent_frame(self):
>         self.webdriver.switch_frame("parent")
>@@ -283,17 +296,24 @@ class WebDriverVirtualAuthenticatorProtocolPart(VirtualAuthenticatorProtocolPart
>         return self.webdriver.send_session_command("POST", "webauthn/authenticator/%s/uv" % authenticator_id, uv)
> 
> 
>+class WebDriverDebugProtocolPart(DebugProtocolPart):
>+    def load_devtools(self):
>+        raise NotImplementedError()
>+
>+
> class WebDriverProtocol(Protocol):
>     implements = [WebDriverBaseProtocolPart,
>                   WebDriverTestharnessProtocolPart,
>                   WebDriverSelectorProtocolPart,
>                   WebDriverClickProtocolPart,
>+                  WebDriverCookiesProtocolPart,
>                   WebDriverSendKeysProtocolPart,
>                   WebDriverActionSequenceProtocolPart,
>                   WebDriverTestDriverProtocolPart,
>                   WebDriverGenerateTestReportProtocolPart,
>                   WebDriverSetPermissionProtocolPart,
>-                  WebDriverVirtualAuthenticatorProtocolPart]
>+                  WebDriverVirtualAuthenticatorProtocolPart,
>+                  WebDriverDebugProtocolPart]
> 
>     def __init__(self, executor, browser, capabilities, **kwargs):
>         super(WebDriverProtocol, self).__init__(executor, browser)
>@@ -308,7 +328,7 @@ class WebDriverProtocol(Protocol):
>         host, port = self.url.split(":")[1].strip("/"), self.url.split(':')[-1].strip("/")
> 
>         capabilities = {"alwaysMatch": self.capabilities}
>-        self.webdriver = client.Session(host, port, capabilities=capabilities)
>+        self.webdriver = Session(host, port, capabilities=capabilities)
>         self.webdriver.start()
> 
>     def teardown(self):
>@@ -331,7 +351,7 @@ class WebDriverProtocol(Protocol):
>             # 5 seconds of extra_timeout we have as maximum to end the test before
>             # the external timeout from testrunner triggers.
>             self.webdriver.send_session_command("GET", "window", timeout=2)
>-        except (socket.timeout, client.UnknownErrorException, client.InvalidSessionIdException):
>+        except (socket.timeout, error.UnknownErrorException, error.InvalidSessionIdException):
>             return False
>         return True
> 
>@@ -343,19 +363,20 @@ class WebDriverRun(TimedRunner):
>     def set_timeout(self):
>         try:
>             self.protocol.base.set_timeout(self.timeout + self.extra_timeout)
>-        except client.UnknownErrorException:
>-            self.logger.error("Lost WebDriver connection")
>-            return Stop
>+        except error.UnknownErrorException:
>+            msg = "Lost WebDriver connection"
>+            self.logger.error(msg)
>+            return ("INTERNAL-ERROR", msg)
> 
>     def run_func(self):
>         try:
>             self.result = True, self.func(self.protocol, self.url, self.timeout)
>-        except (client.TimeoutException, client.ScriptTimeoutException):
>+        except (error.TimeoutException, error.ScriptTimeoutException):
>             self.result = False, ("EXTERNAL-TIMEOUT", None)
>-        except (socket.timeout, client.UnknownErrorException):
>+        except (socket.timeout, error.UnknownErrorException):
>             self.result = False, ("CRASH", None)
>         except Exception as e:
>-            if (isinstance(e, client.WebDriverException) and
>+            if (isinstance(e, error.WebDriverException) and
>                     e.http_status == 408 and
>                     e.status_code == "asynchronous script timeout"):
>                 # workaround for https://bugs.chromium.org/p/chromedriver/issues/detail?id=2001
>@@ -449,7 +470,7 @@ class WebDriverTestharnessExecutor(TestharnessExecutor):
>             if not isinstance(result, list) or len(result) != 2:
>                 try:
>                     is_alive = self.is_alive()
>-                except client.WebDriverException:
>+                except error.WebDriverException:
>                     is_alive = False
> 
>                 if not is_alive:
>@@ -483,7 +504,7 @@ if (location.href === "about:blank") {
> } else {
>   document.addEventListener("readystatechange", () => {if (document.readyState !== "loading") {callback(true)}});
> }""", asynchronous=True)
>-            except client.JavascriptErrorException:
>+            except error.JavascriptErrorException:
>                 # We can get an error here if the script runs in the initial about:blank
>                 # document before it has navigated, with the driver returning an error
>                 # indicating that the document was unloaded
>@@ -497,7 +518,7 @@ class WebDriverRefTestExecutor(RefTestExecutor):
> 
>     def __init__(self, logger, browser, server_config, timeout_multiplier=1,
>                  screenshot_cache=None, close_after_done=True,
>-                 debug_info=None, capabilities=None, **kwargs):
>+                 debug_info=None, capabilities=None, debug_test=False, **kwargs):
>         """WebDriver-based executor for reftests"""
>         RefTestExecutor.__init__(self,
>                                  logger,
>@@ -512,6 +533,7 @@ class WebDriverRefTestExecutor(RefTestExecutor):
>         self.implementation = RefTestImplementation(self)
>         self.close_after_done = close_after_done
>         self.has_window = False
>+        self.debug_test = debug_test
> 
>         with open(os.path.join(here, "test-wait.js")) as f:
>             self.wait_script = f.read() % {"classname": "reftest-wait"}
>@@ -529,13 +551,16 @@ class WebDriverRefTestExecutor(RefTestExecutor):
>         )
>         try:
>             self.protocol.webdriver.window.position = (0, 0)
>-        except client.InvalidArgumentException:
>+        except error.InvalidArgumentException:
>             # Safari 12 throws with 0 or 1, treating them as bools; fixed in STP
>             self.protocol.webdriver.window.position = (2, 2)
>         self.protocol.webdriver.window.size = (800 + width_offset, 600 + height_offset)
> 
>         result = self.implementation.run_test(test)
> 
>+        if self.debug_test and result["status"] in ["PASS", "FAIL", "ERROR"] and "extra" in result:
>+            self.protocol.debug.load_reftest_analyzer(test, result)
>+
>         return self.convert_result(test, result)
> 
>     def screenshot(self, test, viewport_size, dpi, page_ranges):
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/protocol.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/protocol.py
>index bd768b1073c7..f9547ad904bc 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/protocol.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/protocol.py
>@@ -1,6 +1,7 @@
> import traceback
> 
> from abc import ABCMeta, abstractmethod
>+from typing import ClassVar, List, Type
> 
> 
> class Protocol(object):
>@@ -16,7 +17,7 @@ class Protocol(object):
>     :param Browser browser: The Browser using this protocol"""
>     __metaclass__ = ABCMeta
> 
>-    implements = []
>+    implements = []  # type: ClassVar[List[Type[ProtocolPart]]]
> 
>     def __init__(self, executor, browser):
>         self.executor = executor
>@@ -82,7 +83,7 @@ class ProtocolPart(object):
>     :param Protocol parent: The parent protocol"""
>     __metaclass__ = ABCMeta
> 
>-    name = None
>+    name = None  # type: ClassVar[str]
> 
>     def __init__(self, parent):
>         self.parent = parent
>@@ -281,6 +282,18 @@ class ClickProtocolPart(ProtocolPart):
>         pass
> 
> 
>+class CookiesProtocolPart(ProtocolPart):
>+    """Protocol part for managing cookies"""
>+    __metaclass__ = ABCMeta
>+
>+    name = "cookies"
>+
>+    @abstractmethod
>+    def delete_all_cookies(self):
>+        """Delete all cookies."""
>+        pass
>+
>+
> class SendKeysProtocolPart(ProtocolPart):
>     """Protocol part for performing trusted clicks"""
>     __metaclass__ = ABCMeta
>@@ -358,43 +371,72 @@ class TestDriverProtocolPart(ProtocolPart):
>         :param str message: Additional data to add to the message."""
>         pass
> 
>-    def switch_to_window(self, wptrunner_id):
>+    def switch_to_window(self, wptrunner_id, initial_window=None):
>         """Switch to a window given a wptrunner window id
> 
>-        :param str wptrunner_id: window id"""
>+        :param str wptrunner_id: Testdriver-specific id for the target window
>+        :param str initial_window: WebDriver window id for the test window"""
>         if wptrunner_id is None:
>             return
> 
>+        if initial_window is None:
>+            initial_window = self.parent.base.current_window
>+
>         stack = [str(item) for item in self.parent.base.window_handles()]
>+        first = True
>         while stack:
>             item = stack.pop()
>+
>             if item is None:
>+                assert first is False
>                 self._switch_to_parent_frame()
>                 continue
>-            elif isinstance(item, str):
>-                self.parent.base.set_window(item)
>+
>+            if isinstance(item, str):
>+                if not first or item != initial_window:
>+                    self.parent.base.set_window(item)
>+                first = False
>             else:
>-                self._switch_to_frame(item)
>+                assert first is False
>+                try:
>+                    self._switch_to_frame(item)
>+                except ValueError:
>+                    # The frame no longer exists, or doesn't have a nested browsing context, so continue
>+                    continue
> 
>             try:
>-                handle_window_id = self.parent.base.execute_script("return window.__wptrunner_id")
>-                if str(handle_window_id) == wptrunner_id:
>-                    return
>+                # Get the window id and a list of elements containing nested browsing contexts.
>+                # For embed we can't tell fpr sure if there's a nested browsing context, so always return it
>+                # and fail later if there isn't
>+                result = self.parent.base.execute_script("""
>+                let contextParents = Array.from(document.querySelectorAll("frame, iframe, embed, object"))
>+                    .filter(elem => elem.localName !== "embed" ? (elem.contentWindow !== null) : true);
>+                return [window.__wptrunner_id, contextParents]""")
>             except Exception:
>-                pass
>-            frame_count = self.parent.base.execute_script("return window.length")
>-            # None here makes us switch back to the parent after we've processed all the subframes
>-            stack.append(None)
>-            if frame_count:
>-                stack.extend(reversed(range(0, frame_count)))
>+                continue
>+
>+            if result is None:
>+                # With marionette at least this is possible if the content process crashed. Not quite
>+                # sure how we want to handle that case.
>+                continue
>+
>+            handle_window_id, nested_context_containers = result
>+
>+            if handle_window_id and str(handle_window_id) == wptrunner_id:
>+                return
>+
>+            for elem in reversed(nested_context_containers):
>+                # None here makes us switch back to the parent after we've processed the frame
>+                stack.append(None)
>+                stack.append(elem)
> 
>         raise Exception("Window with id %s not found" % wptrunner_id)
> 
>     @abstractmethod
>-    def _switch_to_frame(self, index):
>+    def _switch_to_frame(self, index_or_elem):
>         """Switch to a frame in the current window
> 
>-        :param int index: Frame id"""
>+        :param int index_or_elem: Frame id or container element"""
>         pass
> 
>     @abstractmethod
>@@ -503,3 +545,32 @@ class PrintProtocolPart(ProtocolPart):
>     def render_as_pdf(self, width, height):
>         """Output document as PDF"""
>         pass
>+
>+
>+class DebugProtocolPart(ProtocolPart):
>+    """Protocol part for debugging test failures."""
>+    __metaclass__ = ABCMeta
>+
>+    name = "debug"
>+
>+    @abstractmethod
>+    def load_devtools(self):
>+        """Load devtools in the current window"""
>+        pass
>+
>+    def load_reftest_analyzer(self, test, result):
>+        import io
>+        import mozlog
>+        from urllib.parse import quote, urljoin
>+
>+        debug_test_logger = mozlog.structuredlog.StructuredLogger("debug_test")
>+        output = io.StringIO()
>+        debug_test_logger.suite_start([])
>+        debug_test_logger.add_handler(mozlog.handlers.StreamHandler(output, formatter=mozlog.formatters.TbplFormatter()))
>+        debug_test_logger.test_start(test.id)
>+        # Always use PASS as the expected value so we get output even for expected failures
>+        debug_test_logger.test_end(test.id, result["status"], "PASS", extra=result.get("extra"))
>+
>+        self.parent.base.load(urljoin(self.parent.executor.server_url("https"),
>+                              "/common/third_party/reftest-analyzer.xhtml#log=%s" %
>+                               quote(output.getvalue())))
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/pytestrunner/runner.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/pytestrunner/runner.py
>index 3d32917659b3..50819a935899 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/pytestrunner/runner.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/executors/pytestrunner/runner.py
>@@ -24,7 +24,7 @@ def do_delayed_imports():
>     import pytest
> 
> 
>-def run(path, server_config, session_config, timeout=0):
>+def run(path, server_config, session_config, timeout=0, environ=None):
>     """
>     Run Python test at ``path`` in pytest.  The provided ``session``
>     is exposed as a fixture available in the scope of the test functions.
>@@ -41,28 +41,40 @@ def run(path, server_config, session_config, timeout=0):
>     if pytest is None:
>         do_delayed_imports()
> 
>-    os.environ["WD_HOST"] = session_config["host"]
>-    os.environ["WD_PORT"] = str(session_config["port"])
>-    os.environ["WD_CAPABILITIES"] = json.dumps(session_config["capabilities"])
>-    os.environ["WD_SERVER_CONFIG"] = json.dumps(server_config.as_dict_for_wd_env_variable())
>-
>-    harness = HarnessResultRecorder()
>-    subtests = SubtestResultRecorder()
>-
>-    with TemporaryDirectory() as cache:
>-        try:
>-            pytest.main(["--strict",  # turn warnings into errors
>-                         "-vv",  # show each individual subtest and full failure logs
>-                         "--capture", "no",  # enable stdout/stderr from tests
>-                         "--basetemp", cache,  # temporary directory
>-                         "--showlocals",  # display contents of variables in local scope
>-                         "-p", "no:mozlog",  # use the WPT result recorder
>-                         "-p", "no:cacheprovider",  # disable state preservation across invocations
>-                         "-o=console_output_style=classic",  # disable test progress bar
>-                         path],
>-                        plugins=[harness, subtests])
>-        except Exception as e:
>-            harness.outcome = ("INTERNAL-ERROR", str(e))
>+    old_environ = os.environ.copy()
>+    try:
>+        with TemporaryDirectory() as cache:
>+            os.environ["WD_HOST"] = session_config["host"]
>+            os.environ["WD_PORT"] = str(session_config["port"])
>+            os.environ["WD_CAPABILITIES"] = json.dumps(session_config["capabilities"])
>+
>+            config_path = os.path.join(cache, "wd_server_config.json")
>+            os.environ["WD_SERVER_CONFIG_FILE"] = config_path
>+            with open(config_path, "w") as f:
>+                json.dump(server_config.as_dict(), f)
>+
>+            if environ:
>+                os.environ.update(environ)
>+
>+            harness = HarnessResultRecorder()
>+            subtests = SubtestResultRecorder()
>+
>+            try:
>+                pytest.main(["--strict",  # turn warnings into errors
>+                             "-vv",  # show each individual subtest and full failure logs
>+                             "--capture", "no",  # enable stdout/stderr from tests
>+                             "--basetemp", cache,  # temporary directory
>+                             "--showlocals",  # display contents of variables in local scope
>+                             "-p", "no:mozlog",  # use the WPT result recorder
>+                             "-p", "no:cacheprovider",  # disable state preservation across invocations
>+                             "-o=console_output_style=classic",  # disable test progress bar
>+                             path],
>+                            plugins=[harness, subtests])
>+            except Exception as e:
>+                harness.outcome = ("INTERNAL-ERROR", str(e))
>+
>+    finally:
>+        os.environ = old_environ
> 
>     return (harness.outcome, subtests.results)
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/font.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/font.py
>index 910358f51596..39e248b251b0 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/font.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/font.py
>@@ -77,13 +77,15 @@ class FontInstaller(object):
> 
>         # Per https://github.com/web-platform-tests/results-collection/issues/218
>         # installing Ahem on macOS is flaky, so check if it actually installed
>-        fonts = check_output(['/usr/sbin/system_profiler', '-xml', 'SPFontsDataType'])
>+        with open(os.devnull, 'w') as f:
>+            fonts = check_output(['/usr/sbin/system_profiler', '-xml', 'SPFontsDataType'], stderr=f)
>+
>         try:
>             # if py3
>-            readPlistFromBytes = plistlib.readPlistFromBytes
>+            load_plist = plistlib.loads
>         except AttributeError:
>-            readPlistFromBytes = plistlib.readPlistFromString
>-        fonts = readPlistFromBytes(fonts)
>+            load_plist = plistlib.readPlistFromString
>+        fonts = load_plist(fonts)
>         assert len(fonts) == 1
>         for font in fonts[0]['_items']:
>             if font['path'] == installed_font_path:
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/formatters/tests/__init__.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/formatters/tests/__init__.py
>new file mode 100644
>index 000000000000..e69de29bb2d1
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/instruments.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/instruments.py
>index a887cf4fda72..4e3e013aec43 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/instruments.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/instruments.py
>@@ -1,6 +1,6 @@
> import time
> import threading
>-from six.moves.queue import Queue
>+from queue import Queue
> 
> """Instrumentation for measuring high-level time spent on various tasks inside the runner.
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestexpected.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestexpected.py
>index 31c57e9cb734..1cd035a3b243 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestexpected.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestexpected.py
>@@ -1,8 +1,6 @@
> import os
> from collections import deque
>-from six import string_types, text_type
>-from six.moves.urllib.parse import urljoin
>-
>+from urllib.parse import urljoin
> 
> from .wptmanifest.backends import static
> from .wptmanifest.backends.base import ManifestItem
>@@ -49,7 +47,7 @@ def list_prop(name, node):
>     """List property"""
>     try:
>         list_prop = node.get(name)
>-        if isinstance(list_prop, string_types):
>+        if isinstance(list_prop, str):
>             return [list_prop]
>         return list(list_prop)
>     except KeyError:
>@@ -59,7 +57,7 @@ def list_prop(name, node):
> def str_prop(name, node):
>     try:
>         prop = node.get(name)
>-        if not isinstance(prop, string_types):
>+        if not isinstance(prop, str):
>             raise ValueError
>         return prop
>     except KeyError:
>@@ -70,7 +68,7 @@ def tags(node):
>     """Set of tags that have been applied to the test"""
>     try:
>         value = node.get("tags")
>-        if isinstance(value, text_type):
>+        if isinstance(value, str):
>             return {value}
>         return set(value)
>     except KeyError:
>@@ -79,7 +77,7 @@ def tags(node):
> 
> def prefs(node):
>     def value(ini_value):
>-        if isinstance(ini_value, text_type):
>+        if isinstance(ini_value, str):
>             return tuple(pref_piece.strip() for pref_piece in ini_value.split(':', 1))
>         else:
>             # this should be things like @Reset, which are apparently type 'object'
>@@ -87,7 +85,7 @@ def prefs(node):
> 
>     try:
>         node_prefs = node.get("prefs")
>-        if isinstance(node_prefs, text_type):
>+        if isinstance(node_prefs, str):
>             rv = dict(value(node_prefs))
>         else:
>             rv = dict(value(item) for item in node_prefs)
>@@ -99,7 +97,7 @@ def prefs(node):
> def set_prop(name, node):
>     try:
>         node_items = node.get(name)
>-        if isinstance(node_items, text_type):
>+        if isinstance(node_items, str):
>             rv = {node_items}
>         else:
>             rv = set(node_items)
>@@ -112,7 +110,7 @@ def leak_threshold(node):
>     rv = {}
>     try:
>         node_items = node.get("leak-threshold")
>-        if isinstance(node_items, text_type):
>+        if isinstance(node_items, str):
>             node_items = [node_items]
>         for item in node_items:
>             process, value = item.rsplit(":", 1)
>@@ -140,7 +138,7 @@ def fuzzy_prop(node):
>       maxDifferences=10;totalPixels=10-20
> 
>       specifies that for any test/ref pair for which no other rule is supplied,
>-      there must be a maximum pixel difference of exactly 10, and betwen 10 and
>+      there must be a maximum pixel difference of exactly 10, and between 10 and
>       20 total pixels different.
> 
>       test.html==ref.htm:10;20
>@@ -169,7 +167,7 @@ def fuzzy_prop(node):
>     if not isinstance(value, list):
>         value = [value]
>     for item in value:
>-        if not isinstance(item, text_type):
>+        if not isinstance(item, str):
>             rv.append(item)
>             continue
>         parts = item.rsplit(":", 1)
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestinclude.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestinclude.py
>index 79b5b19b3a3f..97348e6d52f9 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestinclude.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestinclude.py
>@@ -6,8 +6,7 @@ be included or excluded.
> """
> import glob
> import os
>-from six import iteritems
>-from six.moves.urllib.parse import urlparse, urlsplit
>+from urllib.parse import urlparse, urlsplit
> 
> from .wptmanifest.node import DataNode
> from .wptmanifest.backends import conditional
>@@ -95,7 +94,7 @@ class IncludeManifest(ManifestItem):
>         if paths:
>             urls = []
>             for path in paths:
>-                for manifest, data in iteritems(test_manifests):
>+                for manifest, data in test_manifests.items():
>                     found = False
>                     rel_path = os.path.relpath(path, data["tests_path"])
>                     iterator = manifest.iterpath if os.path.isfile(path) else manifest.iterdir
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestupdate.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestupdate.py
>index 129457b3fd12..b25d49b0fb7c 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestupdate.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/manifestupdate.py
>@@ -1,9 +1,8 @@
>-from __future__ import print_function
> import os
>-from six.moves.urllib.parse import urljoin, urlsplit
>+from urllib.parse import urljoin, urlsplit
> from collections import namedtuple, defaultdict, deque
> from math import ceil
>-from six import integer_types, iterkeys, itervalues, iteritems, string_types, text_type
>+from typing import Any, Callable, ClassVar, Dict, List
> 
> from .wptmanifest import serialize
> from .wptmanifest.node import (DataNode, ConditionalNode, BinaryExpressionNode,
>@@ -76,7 +75,7 @@ class UpdateProperties(object):
>         return name in self._classes
> 
>     def __iter__(self):
>-        for name in iterkeys(self._classes):
>+        for name in self._classes.keys():
>             yield getattr(self, name)
> 
> 
>@@ -313,18 +312,21 @@ def build_conditional_tree(_, run_info_properties, results):
> 
> def build_unconditional_tree(_, run_info_properties, results):
>     root = expectedtree.Node(None, None)
>-    for run_info, values in iteritems(results):
>-        for value, count in iteritems(values):
>+    for run_info, values in results.items():
>+        for value, count in values.items():
>             root.result_values[value] += count
>         root.run_info.add(run_info)
>     return root
> 
> 
> class PropertyUpdate(object):
>-    property_name = None
>-    cls_default_value = None
>-    value_type = None
>-    property_builder = None
>+    property_name = None  # type: ClassVar[str]
>+    cls_default_value = None  # type: ClassVar[Any]
>+    value_type = None  # type: ClassVar[type]
>+    # property_builder is a class variable set to either build_conditional_tree
>+    # or build_unconditional_tree. TODO: Make this type stricter when those
>+    # methods are annotated.
>+    property_builder = None  # type: ClassVar[Callable[..., Any]]
> 
>     def __init__(self, node):
>         self.node = node
>@@ -411,7 +413,7 @@ class PropertyUpdate(object):
>         for e in errors:
>             if disable_intermittent:
>                 condition = e.cond.children[0] if e.cond else None
>-                msg = disable_intermittent if isinstance(disable_intermittent, string_types+(text_type,)) else "unstable"
>+                msg = disable_intermittent if isinstance(disable_intermittent, str) else "unstable"
>                 self.node.set("disabled", msg, condition)
>                 self.node.new_disabled = True
>             else:
>@@ -499,7 +501,7 @@ class PropertyUpdate(object):
>                           for run_info in node.run_info}
> 
>         node_by_run_info = {run_info: node
>-                            for (run_info, node) in iteritems(run_info_index)
>+                            for (run_info, node) in run_info_index.items()
>                             if node.result_values}
> 
>         run_info_by_condition = self.run_info_by_condition(run_info_index,
>@@ -512,7 +514,7 @@ class PropertyUpdate(object):
>             # using the properties we've specified and not matching any run_info
>             top_level_props, dependent_props = self.node.root.run_info_properties
>             update_properties = set(top_level_props)
>-            for item in itervalues(dependent_props):
>+            for item in dependent_props.values():
>                 update_properties |= set(item)
>             for condition in current_conditions:
>                 if ((not condition.variables.issubset(update_properties) and
>@@ -614,7 +616,8 @@ class PropertyUpdate(object):
>                     except ConditionError:
>                         expr = make_expr(prop_set, value)
>                         error = ConditionError(expr)
>-                    expr = make_expr(prop_set, value)
>+                    else:
>+                        expr = make_expr(prop_set, value)
>                 else:
>                     # The root node needs special handling
>                     expr = None
>@@ -695,7 +698,7 @@ class ExpectedUpdate(PropertyUpdate):
>             raise ConditionError
> 
>         counts = {}
>-        for status, count in iteritems(new):
>+        for status, count in new.items():
>             if isinstance(status, tuple):
>                 counts[status[0]] = count
>                 counts.update({intermittent: 0 for intermittent in status[1:] if intermittent not in counts})
>@@ -709,24 +712,27 @@ class ExpectedUpdate(PropertyUpdate):
>         # Counts with 0 are considered intermittent.
>         statuses = ["OK", "PASS", "FAIL", "ERROR", "TIMEOUT", "CRASH"]
>         status_priority = {value: i for i, value in enumerate(statuses)}
>-        sorted_new = sorted(iteritems(counts), key=lambda x:(-1 * x[1],
>-                                                           status_priority.get(x[0],
>-                                                           len(status_priority))))
>+        sorted_new = sorted(counts.items(), key=lambda x:(-1 * x[1],
>+                                                        status_priority.get(x[0],
>+                                                        len(status_priority))))
>         expected = []
>         for status, count in sorted_new:
>             # If we are not removing existing recorded intermittents, with a count of 0,
>             # add them in to expected.
>             if count > 0 or not self.remove_intermittent:
>                 expected.append(status)
>+
>+        # If the new intermittent is a subset of the existing one, just use the existing one
>+        # This prevents frequent flip-flopping of results between e.g. [OK, TIMEOUT] and
>+        # [TIMEOUT, OK]
>+        if current and set(expected).issubset(set(current)):
>+            return current
>+
>         if self.update_intermittent:
>             if len(expected) == 1:
>                 return expected[0]
>             return expected
> 
>-        # If nothing has changed and not self.update_intermittent, preserve existing
>-        # intermittent.
>-        if set(expected).issubset(set(current)):
>-            return current
>         # If we are not updating intermittents, return the status with the highest occurence.
>         return expected[0]
> 
>@@ -762,7 +768,7 @@ class MinAssertsUpdate(PropertyUpdate):
> 
> 
> class AppendOnlyListUpdate(PropertyUpdate):
>-    cls_default_value = []
>+    cls_default_value = []  # type: ClassVar[List[str]]
>     property_builder = build_unconditional_tree
> 
>     def updated_value(self, current, new):
>@@ -774,7 +780,7 @@ class AppendOnlyListUpdate(PropertyUpdate):
>         for item in new:
>             if item is None:
>                 continue
>-            elif isinstance(item, text_type):
>+            elif isinstance(item, str):
>                 rv.add(item)
>             else:
>                 rv |= item
>@@ -815,14 +821,14 @@ class LeakObjectUpdate(AppendOnlyListUpdate):
> 
> class LeakThresholdUpdate(PropertyUpdate):
>     property_name = "leak-threshold"
>-    cls_default_value = {}
>+    cls_default_value = {}  # type: ClassVar[Dict[str, int]]
>     property_builder = build_unconditional_tree
> 
>     def from_result_value(self, result):
>         return result
> 
>     def to_ini_value(self, data):
>-        return ["%s:%s" % item for item in sorted(iteritems(data))]
>+        return ["%s:%s" % item for item in sorted(data.items())]
> 
>     def from_ini_value(self, data):
>         rv = {}
>@@ -897,10 +903,10 @@ def make_expr(prop_set, rhs):
> 
> 
> def make_node(value):
>-    if isinstance(value, integer_types+(float,)):
>+    if isinstance(value, (int, float,)):
>         node = NumberNode(value)
>-    elif isinstance(value, text_type):
>-        node = StringNode(text_type(value))
>+    elif isinstance(value, str):
>+        node = StringNode(str(value))
>     elif hasattr(value, "__iter__"):
>         node = ListNode()
>         for item in value:
>@@ -909,14 +915,14 @@ def make_node(value):
> 
> 
> def make_value_node(value):
>-    if isinstance(value, integer_types+(float,)):
>+    if isinstance(value, (int, float,)):
>         node = ValueNode(value)
>-    elif isinstance(value, text_type):
>-        node = ValueNode(text_type(value))
>+    elif isinstance(value, str):
>+        node = ValueNode(str(value))
>     elif hasattr(value, "__iter__"):
>         node = ListNode()
>         for item in value:
>-            node.append(make_node(item))
>+            node.append(make_value_node(item))
>     else:
>         raise ValueError("Don't know how to convert %s into node" % type(value))
>     return node
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/metadata.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/metadata.py
>index ab8d4740f3fc..9c54e570c01b 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/metadata.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/metadata.py
>@@ -1,12 +1,11 @@
>-from __future__ import print_function
> import array
> import os
>-import sys
> from collections import defaultdict, namedtuple
>+from typing import Dict, List, Tuple
> 
> from mozlog import structuredlog
>-from six import ensure_str, ensure_text, iteritems, iterkeys, itervalues, text_type
>-from six.moves import intern, range
>+from six import ensure_str, ensure_text
>+from sys import intern
> 
> from . import manifestupdate
> from . import testloader
>@@ -22,7 +21,7 @@ logger = structuredlog.StructuredLogger("web-platform-tests")
> try:
>     import ujson as json
> except ImportError:
>-    import json
>+    import json  # type: ignore
> 
> 
> class RunInfo(object):
>@@ -45,11 +44,11 @@ class RunInfo(object):
>         return self.canonical_repr == other.canonical_repr
> 
>     def iteritems(self):
>-        for key, value in iteritems(self.data):
>+        for key, value in self.data.items():
>             yield key, value
> 
>     def items(self):
>-        return list(iteritems(self))
>+        return list(self.items())
> 
> 
> def update_expected(test_paths, serve_root, log_file_names,
>@@ -93,7 +92,7 @@ def update_expected(test_paths, serve_root, log_file_names,
> 
> def do_delayed_imports(serve_root=None):
>     global manifest, manifestitem
>-    from manifest import manifest, item as manifestitem
>+    from manifest import manifest, item as manifestitem  # type: ignore
> 
> 
> def files_in_repo(repo_root):
>@@ -129,7 +128,7 @@ def unexpected_changes(manifests, change_data, files_changed):
>     files_changed = set(files_changed)
> 
>     root_manifest = None
>-    for manifest, paths in iteritems(manifests):
>+    for manifest, paths in manifests.items():
>         if paths["url_base"] == "/":
>             root_manifest = manifest
>             break
>@@ -170,9 +169,10 @@ class InternedData(object):
>     type_conv = None
>     rev_type_conv = None
> 
>-    def __init__(self, max_bits=8):
>+    def __init__(self, max_bits: int = 8):
>         self.max_idx = 2**max_bits - 2
>         # Reserve 0 as a sentinal
>+        self._data: Tuple[List[object], Dict[int, object]]
>         self._data = [None], {}
> 
>     def clear(self):
>@@ -240,7 +240,7 @@ def pack_result(data):
> def unpack_result(data):
>     if isinstance(data, int):
>         return (status_intern.get(data), None)
>-    if isinstance(data, text_type):
>+    if isinstance(data, str):
>         return (data, None)
>     # Unpack multiple statuses into a tuple to be used in the Results named tuple below,
>     # separating `status` and `known_intermittent`.
>@@ -259,7 +259,7 @@ def load_test_data(test_paths):
>     manifests = manifest_loader.load()
> 
>     id_test_map = {}
>-    for test_manifest, paths in iteritems(manifests):
>+    for test_manifest, paths in manifests.items():
>         id_test_map.update(create_test_tree(paths["metadata_path"],
>                                             test_manifest))
>     return id_test_map
>@@ -287,10 +287,10 @@ def update_results(id_test_map,
>                    disable_intermittent,
>                    update_intermittent,
>                    remove_intermittent):
>-    test_file_items = set(itervalues(id_test_map))
>+    test_file_items = set(id_test_map.values())
> 
>     default_expected_by_type = {}
>-    for test_type, test_cls in iteritems(wpttest.manifest_test_cls):
>+    for test_type, test_cls in wpttest.manifest_test_cls.items():
>         if test_cls.result_cls:
>             default_expected_by_type[(test_type, False)] = test_cls.result_cls.default_expected
>         if test_cls.subtest_result_cls:
>@@ -327,10 +327,7 @@ def write_new_expected(metadata_path, expected):
>         try:
>             with open(tmp_path, "wb") as f:
>                 f.write(manifest_str.encode("utf8"))
>-            if sys.version_info >= (3, 3):
>-                os.replace(tmp_path, path)
>-            else:
>-                os.rename(tmp_path, path)
>+            os.replace(tmp_path, path)
>         except (Exception, KeyboardInterrupt):
>             try:
>                 os.unlink(tmp_path)
>@@ -431,7 +428,7 @@ class ExpectedUpdater(object):
>             action_map["lsan_leak"](item)
> 
>         mozleak_data = data.get("mozleak", {})
>-        for scope, scope_data in iteritems(mozleak_data):
>+        for scope, scope_data in mozleak_data.items():
>             for key, action in [("objects", "mozleak_object"),
>                                 ("total", "mozleak_total")]:
>                 for item in scope_data.get(key, []):
>@@ -668,11 +665,11 @@ class TestFileData(object):
>         # Return subtest nodes present in the expected file, but missing from the data
>         rv = []
> 
>-        for test_id, subtests in iteritems(self.data):
>+        for test_id, subtests in self.data.items():
>             test = expected.get_test(ensure_text(test_id))
>             if not test:
>                 continue
>-            seen_subtests = set(ensure_text(item) for item in iterkeys(subtests) if item is not None)
>+            seen_subtests = set(ensure_text(item) for item in subtests.keys() if item is not None)
>             missing_subtests = set(test.subtests.keys()) - seen_subtests
>             for item in missing_subtests:
>                 expected_subtest = test.get_subtest(item)
>@@ -691,7 +688,7 @@ class TestFileData(object):
>         # since removing these may be inappropriate
>         top_level_props, dependent_props = update_properties
>         all_properties = set(top_level_props)
>-        for item in itervalues(dependent_props):
>+        for item in dependent_props.values():
>             all_properties |= set(item)
> 
>         filtered = []
>@@ -741,9 +738,9 @@ class TestFileData(object):
>             test_expected = expected.get_test(test_id)
>             expected_by_test[test_id] = test_expected
> 
>-        for test_id, test_data in iteritems(self.data):
>+        for test_id, test_data in self.data.items():
>             test_id = ensure_str(test_id)
>-            for subtest_id, results_list in iteritems(test_data):
>+            for subtest_id, results_list in test_data.items():
>                 for prop, run_info, value in results_list:
>                     # Special case directory metadata
>                     if subtest_id is None and test_id.endswith("__dir__"):
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/mpcontext.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/mpcontext.py
>new file mode 100644
>index 000000000000..a50c04782a65
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/mpcontext.py
>@@ -0,0 +1,11 @@
>+import multiprocessing
>+
>+_context = None
>+
>+
>+def get_context():
>+    global _context
>+
>+    if _context is None:
>+        _context = multiprocessing.get_context("spawn")
>+    return _context
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/process.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/process.py
>deleted file mode 100644
>index 8a2b894cb74d..000000000000
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/process.py
>+++ /dev/null
>@@ -1,11 +0,0 @@
>-import sys
>-
>-import six
>-
>-
>-def cast_env(env):
>-    """Encode all the environment values as the appropriate type for each Python version
>-    This assumes that all the data is or can be represented as UTF8"""
>-
>-    env_type = six.ensure_binary if sys.version_info[0] < 3 else six.ensure_str
>-    return {env_type(key): env_type(value) for key, value in six.iteritems(env)}
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/products.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/products.py
>index abd84094bb33..e65df5ee8993 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/products.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/products.py
>@@ -1,6 +1,5 @@
> import importlib
> import imp
>-from six import iteritems
> 
> from .browsers import product_list
> 
>@@ -34,34 +33,29 @@ class Product(object):
>         module = product_module(config, product)
>         data = module.__wptrunner__
>         self.name = product
>+        if isinstance(data["browser"], str):
>+            self._browser_cls = {None: getattr(module, data["browser"])}
>+        else:
>+            self._browser_cls = {key: getattr(module, value)
>+                                 for key, value in data["browser"].items()}
>         self.check_args = getattr(module, data["check_args"])
>-        self.browser_cls = getattr(module, data["browser"])
>         self.get_browser_kwargs = getattr(module, data["browser_kwargs"])
>         self.get_executor_kwargs = getattr(module, data["executor_kwargs"])
>         self.env_options = getattr(module, data["env_options"])()
>         self.get_env_extras = getattr(module, data["env_extras"])
>         self.run_info_extras = (getattr(module, data["run_info_extras"])
>-                           if "run_info_extras" in data else lambda **kwargs:{})
>+                                if "run_info_extras" in data else lambda **kwargs:{})
>         self.get_timeout_multiplier = getattr(module, data["timeout_multiplier"])
> 
>         self.executor_classes = {}
>-        for test_type, cls_name in iteritems(data["executor"]):
>+        for test_type, cls_name in data["executor"].items():
>             cls = getattr(module, cls_name)
>             self.executor_classes[test_type] = cls
> 
>-
>-def load_product(config, product, load_cls=False):
>-    rv = Product(config, product)
>-    if not load_cls:
>-        return (rv.check_args,
>-                rv.browser_cls,
>-                rv.get_browser_kwargs,
>-                rv.executor_classes,
>-                rv.get_executor_kwargs,
>-                rv.env_options,
>-                rv.get_env_extras,
>-                rv.run_info_extras)
>-    return rv
>+    def get_browser_cls(self, test_type):
>+        if test_type in self._browser_cls:
>+            return self._browser_cls[test_type]
>+        return self._browser_cls[None]
> 
> 
> def load_product_update(config, product):
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/stability.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/stability.py
>index 88d1c232bfb5..eeb5af230029 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/stability.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/stability.py
>@@ -5,7 +5,6 @@ import io
> import os
> from collections import OrderedDict, defaultdict
> from datetime import datetime
>-from six import iteritems
> 
> from mozlog import reader
> from mozlog.formatters import JSONFormatter
>@@ -13,8 +12,8 @@ from mozlog.handlers import BaseHandler, StreamHandler, LogLevelFilter
> 
> here = os.path.dirname(__file__)
> localpaths = imp.load_source("localpaths", os.path.abspath(os.path.join(here, os.pardir, os.pardir, "localpaths.py")))
>-from ci.tc.github_checks_output import get_gh_checks_outputter
>-from wpt.markdown import markdown_adjust, table
>+from ci.tc.github_checks_output import get_gh_checks_outputter  # type: ignore
>+from wpt.markdown import markdown_adjust, table  # type: ignore
> 
> 
> # If a test takes more than (FLAKY_THRESHOLD*timeout) and does not consistently
>@@ -22,7 +21,7 @@ from wpt.markdown import markdown_adjust, table
> FLAKY_THRESHOLD = 0.8
> 
> 
>-class LogActionFilter(BaseHandler):
>+class LogActionFilter(BaseHandler):  # type: ignore
> 
>     """Handler that filters out messages not of a given set of actions.
> 
>@@ -44,7 +43,7 @@ class LogActionFilter(BaseHandler):
>             return self.inner(item)
> 
> 
>-class LogHandler(reader.LogHandler):
>+class LogHandler(reader.LogHandler):  # type: ignore
> 
>     """Handle updating test and subtest status in log.
> 
>@@ -142,10 +141,10 @@ def process_results(log, iterations):
>     handler = LogHandler()
>     reader.handle_log(reader.read(log), handler)
>     results = handler.results
>-    for test_name, test in iteritems(results):
>+    for test_name, test in results.items():
>         if is_inconsistent(test["status"], iterations):
>             inconsistent.append((test_name, None, test["status"], []))
>-        for subtest_name, subtest in iteritems(test["subtests"]):
>+        for subtest_name, subtest in test["subtests"].items():
>             if is_inconsistent(subtest["status"], iterations):
>                 inconsistent.append((test_name, subtest_name, subtest["status"], subtest["messages"]))
> 
>@@ -235,7 +234,7 @@ def write_results(log, results, iterations, pr_number=None, use_details=False):
>                                                   "tests" if len(results) > 1
>                                                   else "test"))
> 
>-    for test_name, test in iteritems(results):
>+    for test_name, test in results.items():
>         baseurl = "http://w3c-test.org/submissions"
>         if "https" in os.path.splitext(test_name)[0].split(".")[1:]:
>             baseurl = "https://w3c-test.org/submissions"
>@@ -305,7 +304,7 @@ def get_steps(logger, repeat_loop, repeat_restart, kwargs_extras):
>     for kwargs_extra in kwargs_extras:
>         if kwargs_extra:
>             flags_string = " with flags %s" % " ".join(
>-                "%s=%s" % item for item in iteritems(kwargs_extra))
>+                "%s=%s" % item for item in kwargs_extra.items())
>         else:
>             flags_string = ""
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testdriver-extra.js b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testdriver-extra.js
>index 9c0c69af3a3f..842abf411f90 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testdriver-extra.js
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testdriver-extra.js
>@@ -34,7 +34,7 @@
>         } else if (data.type === "testdriver-complete") {
>             const cmd_id = data.cmd_id;
>             const [on_success, on_failure] = pending.get(cmd_id);
>-            pending.clear(cmd_id);
>+            pending.delete(cmd_id);
>             const resolver = data.status === "success" ? on_success : on_failure;
>             resolver(data);
>             if (is_test_context) {
>@@ -136,6 +136,9 @@
>             if (testharness_context === null) {
>                 throw new Error("Tried to run in a non-testharness window without a call to set_test_context");
>             }
>+            if (action_msg.context === null) {
>+                action_msg.context = get_window_id(window);
>+            }
>             cmd_id = ctx_cmd_id++;
>             action_msg.cmd_id = cmd_id;
>             window.test_driver.message_test({type: "testdriver-command",
>@@ -169,6 +172,10 @@
>         return create_action("click", {selector, context});
>     };
> 
>+    window.test_driver_internal.delete_all_cookies = function(context=null) {
>+        return create_action("delete_all_cookies", {context});
>+    };
>+
>     window.test_driver_internal.send_keys = function(element, keys) {
>         const selector = get_selector(element);
>         const context = get_context(element);
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport-servo.js b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport-servo.js
>index a10b69df5504..4a27dc27ef6f 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport-servo.js
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport-servo.js
>@@ -1,4 +1,4 @@
>-var props = {output:%(output)d};
>+var props = {output:%(output)d, debug: %(debug)s};
> var start_loc = document.createElement('a');
> start_loc.href = location.href;
> setup(props);
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport-servodriver.js b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport-servodriver.js
>index c88841360470..7819538dbb8f 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport-servodriver.js
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport-servodriver.js
>@@ -1,4 +1,4 @@
>-setup({output:%(output)d});
>+setup({output:%(output)d, debug: %(debug)s});
> 
> add_completion_callback(function() {
>     add_completion_callback(function (tests, status) {
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport.js b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport.js
>index 9cd680e14aed..d385692445c5 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport.js
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testharnessreport.js
>@@ -73,6 +73,7 @@ window.__wptrunner_process_next_event = function() {
>   var props = {output: %(output)d,
>                timeout_multiplier: %(timeout_multiplier)s,
>                explicit_timeout: %(explicit_timeout)s,
>+               debug: %(debug)s,
>                message_events: ["completion"]};
> 
>   add_completion_callback(function(tests, harness_status) {
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testloader.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testloader.py
>index 4a3fa4273654..9492a8bc38e6 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testloader.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testloader.py
>@@ -1,16 +1,14 @@
> import hashlib
> import json
> import os
>-from six.moves.urllib.parse import urlsplit
>+from urllib.parse import urlsplit
> from abc import ABCMeta, abstractmethod
>-from six.moves.queue import Empty
>+from queue import Empty
> from collections import defaultdict, deque
>-from multiprocessing import Queue
>-from six import ensure_binary, iteritems
>-from six.moves import range
> 
> from . import manifestinclude
> from . import manifestexpected
>+from . import mpcontext
> from . import wpttest
> from mozlog import structured
> 
>@@ -22,9 +20,9 @@ download_from_github = None
> def do_delayed_imports():
>     # This relies on an already loaded module having set the sys.path correctly :(
>     global manifest, manifest_update, download_from_github
>-    from manifest import manifest
>+    from manifest import manifest  # type: ignore
>     from manifest import update as manifest_update
>-    from manifest.download import download_from_github
>+    from manifest.download import download_from_github  # type: ignore
> 
> 
> class TestGroupsFile(object):
>@@ -41,7 +39,7 @@ class TestGroupsFile(object):
>             raise
> 
>         self.group_by_test = {}
>-        for group, test_ids in iteritems(self._data):
>+        for group, test_ids in self._data.items():
>             for test_id in test_ids:
>                 self.group_by_test[test_id] = group
> 
>@@ -51,6 +49,16 @@ class TestGroupsFile(object):
>     def __getitem__(self, key):
>         return self._data[key]
> 
>+def read_include_from_file(file):
>+    new_include = []
>+    with open(file) as f:
>+        for line in f:
>+            line = line.strip()
>+            # Allow whole-line comments;
>+            # fragments mean we can't have partial line #-based comments
>+            if len(line) > 0 and not line.startswith("#"):
>+                new_include.append(line)
>+    return new_include
> 
> def update_include_for_groups(test_groups, include):
>     if include is None:
>@@ -93,7 +101,7 @@ class HashChunker(TestChunker):
>     def __call__(self, manifest):
>         chunk_index = self.chunk_number - 1
>         for test_type, test_path, tests in manifest:
>-            h = int(hashlib.md5(ensure_binary(test_path)).hexdigest(), 16)
>+            h = int(hashlib.md5(test_path.encode()).hexdigest(), 16)
>             if h % self.total_chunks == chunk_index:
>                 yield test_type, test_path, tests
> 
>@@ -112,7 +120,7 @@ class DirectoryHashChunker(TestChunker):
>                 hash_path = os.path.sep.join(os.path.dirname(test_path).split(os.path.sep, depth)[:depth])
>             else:
>                 hash_path = os.path.dirname(test_path)
>-            h = int(hashlib.md5(ensure_binary(hash_path)).hexdigest(), 16)
>+            h = int(hashlib.md5(hash_path.encode()).hexdigest(), 16)
>             if h % self.total_chunks == chunk_index:
>                 yield test_type, test_path, tests
> 
>@@ -173,7 +181,7 @@ class ManifestLoader(object):
> 
>     def load(self):
>         rv = {}
>-        for url_base, paths in iteritems(self.test_paths):
>+        for url_base, paths in self.test_paths.items():
>             manifest_file = self.load_manifest(url_base=url_base,
>                                                **paths)
>             path_data = {"url_base": url_base}
>@@ -390,7 +398,8 @@ class GroupedSource(TestSource):
> 
>     @classmethod
>     def make_queue(cls, tests, **kwargs):
>-        test_queue = Queue()
>+        mp = mpcontext.get_context()
>+        test_queue = mp.Queue()
>         groups = []
> 
>         state = {}
>@@ -423,7 +432,8 @@ class GroupedSource(TestSource):
> class SingleTestSource(TestSource):
>     @classmethod
>     def make_queue(cls, tests, **kwargs):
>-        test_queue = Queue()
>+        mp = mpcontext.get_context()
>+        test_queue = mp.Queue()
>         processes = kwargs["processes"]
>         queues = [deque([]) for _ in range(processes)]
>         metadatas = [cls.group_metadata(None) for _ in range(processes)]
>@@ -467,9 +477,10 @@ class GroupFileTestSource(TestSource):
> 
>         ids_to_tests = {test.id: test for test in tests}
> 
>-        test_queue = Queue()
>+        mp = mpcontext.get_context()
>+        test_queue = mp.Queue()
> 
>-        for group_name, test_ids in iteritems(tests_by_group):
>+        for group_name, test_ids in tests_by_group.items():
>             group_metadata = {"scope": group_name}
>             group = deque()
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testrunner.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testrunner.py
>index 0bde5ba348ea..4da1255d13b7 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testrunner.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/testrunner.py
>@@ -1,14 +1,12 @@
>-from __future__ import unicode_literals
>-
>-import multiprocessing
> import threading
> import traceback
>-from six.moves.queue import Empty
>+from queue import Empty
> from collections import namedtuple
>-from multiprocessing import Process, current_process, Queue
> 
> from mozlog import structuredlog, capture
> 
>+from . import mpcontext
>+
> # Special value used as a sentinal in various commands
> Stop = object()
> 
>@@ -24,30 +22,12 @@ def release_mozlog_lock():
>         pass
> 
> 
>-class MessageLogger(object):
>-    def __init__(self, message_func):
>-        self.send_message = message_func
>-
>-    def _log_data(self, action, **kwargs):
>-        self.send_message("log", action, kwargs)
>-
>-    def process_output(self, process, data, command):
>-        self._log_data("process_output", process=process, data=data, command=command)
>-
>+class LogMessageHandler:
>+    def __init__(self, send_message):
>+        self.send_message = send_message
> 
>-def _log_func(level_name):
>-    def log(self, message):
>-        self._log_data(level_name.lower(), message=message)
>-    log.__doc__ = """Log a message with level %s
>-
>-:param message: The string message to log
>-""" % level_name
>-    log.__name__ = str(level_name).lower()
>-    return log
>-
>-# Create all the methods on StructuredLog for debug levels
>-for level_name in structuredlog.log_levels:
>-    setattr(MessageLogger, level_name.lower(), _log_func(level_name))
>+    def __call__(self, data):
>+        self.send_message("log", data)
> 
> 
> class TestRunner(object):
>@@ -68,7 +48,7 @@ class TestRunner(object):
>         self.result_queue = result_queue
> 
>         self.executor = executor
>-        self.name = current_process().name
>+        self.name = mpcontext.get_context().current_process().name
>         self.logger = logger
> 
>     def __enter__(self):
>@@ -98,7 +78,12 @@ class TestRunner(object):
>     def run(self):
>         """Main loop accepting commands over the pipe and triggering
>         the associated methods"""
>-        self.setup()
>+        try:
>+            self.setup()
>+        except Exception:
>+            self.logger.warning("An error occured during executor setup:\n%s" %
>+                                traceback.format_exc())
>+            raise
>         commands = {"run_test": self.run_test,
>                     "reset": self.reset,
>                     "stop": self.stop,
>@@ -153,7 +138,9 @@ def start_runner(runner_command_queue, runner_result_queue,
>     # in the logging module unlocked
>     release_mozlog_lock()
> 
>-    logger = MessageLogger(send_message)
>+    proc_name = mpcontext.get_context().current_process().name
>+    logger = structuredlog.StructuredLogger(proc_name)
>+    logger.add_handler(LogMessageHandler(send_message))
> 
>     with capture.CaptureIO(logger, capture_stdio):
>         try:
>@@ -265,7 +252,7 @@ class BrowserManager(object):
> 
> class _RunnerManagerState(object):
>     before_init = namedtuple("before_init", [])
>-    initializing = namedtuple("initializing_browser",
>+    initializing = namedtuple("initializing",
>                               ["test", "test_group", "group_metadata", "failure_count"])
>     running = namedtuple("running", ["test", "test_group", "group_metadata"])
>     restarting = namedtuple("restarting", ["test", "test_group", "group_metadata"])
>@@ -306,9 +293,11 @@ class TestRunnerManager(threading.Thread):
>         self.executor_cls = executor_cls
>         self.executor_kwargs = executor_kwargs
> 
>+        mp = mpcontext.get_context()
>+
>         # Flags used to shut down this thread if we get a sigint
>         self.parent_stop_flag = stop_flag
>-        self.child_stop_flag = multiprocessing.Event()
>+        self.child_stop_flag = mp.Event()
> 
>         self.rerun = rerun
>         self.run_count = 0
>@@ -321,8 +310,8 @@ class TestRunnerManager(threading.Thread):
>         assert recording is not None
>         self.recording = recording
> 
>-        self.command_queue = Queue()
>-        self.remote_queue = Queue()
>+        self.command_queue = mp.Queue()
>+        self.remote_queue = mp.Queue()
> 
>         self.test_runner_proc = None
> 
>@@ -332,6 +321,7 @@ class TestRunnerManager(threading.Thread):
> 
>         self.test_count = 0
>         self.unexpected_count = 0
>+        self.unexpected_pass_count = 0
> 
>         # This may not really be what we want
>         self.daemon = True
>@@ -354,7 +344,8 @@ class TestRunnerManager(threading.Thread):
>         spins."""
>         self.recording.set(["testrunner", "startup"])
>         self.logger = structuredlog.StructuredLogger(self.suite_name)
>-        with self.browser_cls(self.logger, **self.browser_kwargs) as browser:
>+        with self.browser_cls(self.logger, remote_queue=self.command_queue,
>+                              **self.browser_kwargs) as browser:
>             self.browser = BrowserManager(self.logger,
>                                           browser,
>                                           self.command_queue,
>@@ -494,6 +485,7 @@ class TestRunnerManager(threading.Thread):
>                                                    self.state.failure_count + 1)
>         else:
>             self.executor_kwargs["group_metadata"] = self.state.group_metadata
>+            self.executor_kwargs["browser_settings"] = self.browser.browser_settings
>             self.start_test_runner()
> 
>     def start_test_runner(self):
>@@ -514,9 +506,11 @@ class TestRunnerManager(threading.Thread):
>                 executor_browser_kwargs,
>                 self.capture_stdio,
>                 self.child_stop_flag)
>-        self.test_runner_proc = Process(target=start_runner,
>-                                        args=args,
>-                                        name="TestRunner-%i" % self.manager_number)
>+
>+        mp = mpcontext.get_context()
>+        self.test_runner_proc = mp.Process(target=start_runner,
>+                                           args=args,
>+                                           name="TestRunner-%i" % self.manager_number)
>         self.test_runner_proc.start()
>         self.logger.debug("Test runner started")
>         # Now we wait for either an init_succeeded event or an init_failed event
>@@ -605,6 +599,7 @@ class TestRunnerManager(threading.Thread):
>             return
>         if self.timer is not None:
>             self.timer.cancel()
>+
>         # Write the result of each subtest
>         file_result, test_results = results
>         subtest_unexpected = False
>@@ -625,6 +620,11 @@ class TestRunnerManager(threading.Thread):
>                 self.unexpected_count += 1
>                 self.logger.debug("Unexpected count in this thread %i" % self.unexpected_count)
>                 subtest_unexpected = True
>+
>+            is_unexpected_pass = is_unexpected and result.status == "PASS"
>+            if is_unexpected_pass:
>+                self.unexpected_pass_count += 1
>+
>             self.logger.test_status(test.id,
>                                     result.name,
>                                     result.status,
>@@ -633,34 +633,40 @@ class TestRunnerManager(threading.Thread):
>                                     known_intermittent=known_intermittent,
>                                     stack=result.stack)
> 
>-        # We have a couple of status codes that are used internally, but not exposed to the
>-        # user. These are used to indicate that some possibly-broken state was reached
>-        # and we should restart the runner before the next test.
>-        # INTERNAL-ERROR indicates a Python exception was caught in the harness
>-        # EXTERNAL-TIMEOUT indicates we had to forcibly kill the browser from the harness
>-        # because the test didn't return a result after reaching the test-internal timeout
>-        status_subns = {"INTERNAL-ERROR": "ERROR",
>-                        "EXTERNAL-TIMEOUT": "TIMEOUT"}
>         expected = test.expected()
>         known_intermittent = test.known_intermittent()
>-        status = status_subns.get(file_result.status, file_result.status)
>+        status = file_result.status
> 
>         if self.browser.check_crash(test.id) and status != "CRASH":
>-            if test.test_type == "crashtest":
>+            if test.test_type == "crashtest" or status == "EXTERNAL-TIMEOUT":
>                 self.logger.info("Found a crash dump file; changing status to CRASH")
>                 status = "CRASH"
>             else:
>                 self.logger.warning("Found a crash dump; should change status from %s to CRASH but this causes instability" % (status,))
> 
>+        # We have a couple of status codes that are used internally, but not exposed to the
>+        # user. These are used to indicate that some possibly-broken state was reached
>+        # and we should restart the runner before the next test.
>+        # INTERNAL-ERROR indicates a Python exception was caught in the harness
>+        # EXTERNAL-TIMEOUT indicates we had to forcibly kill the browser from the harness
>+        # because the test didn't return a result after reaching the test-internal timeout
>+        status_subns = {"INTERNAL-ERROR": "ERROR",
>+                        "EXTERNAL-TIMEOUT": "TIMEOUT"}
>+        status = status_subns.get(status, status)
>+
>         self.test_count += 1
>         is_unexpected = expected != status and status not in known_intermittent
>         if is_unexpected:
>             self.unexpected_count += 1
>             self.logger.debug("Unexpected count in this thread %i" % self.unexpected_count)
> 
>+        is_unexpected_pass = is_unexpected and status == "OK"
>+        if is_unexpected_pass:
>+            self.unexpected_pass_count += 1
>+
>         if "assertion_count" in file_result.extra:
>-            assertion_count = file_result.extra.pop("assertion_count")
>-            if assertion_count > 0:
>+            assertion_count = file_result.extra["assertion_count"]
>+            if assertion_count is not None and assertion_count > 0:
>                 self.logger.assertion_count(test.id,
>                                             int(assertion_count),
>                                             test.min_assertion_count,
>@@ -722,8 +728,8 @@ class TestRunnerManager(threading.Thread):
>         self.stop_runner()
>         return RunnerManagerState.initializing(self.state.test, self.state.test_group, self.state.group_metadata, 0)
> 
>-    def log(self, action, kwargs):
>-        getattr(self.logger, action)(**kwargs)
>+    def log(self, data):
>+        self.logger.log_raw(data)
> 
>     def error(self, message):
>         self.logger.error(message)
>@@ -761,20 +767,26 @@ class TestRunnerManager(threading.Thread):
>         self.logger.debug("waiting for runner process to end")
>         self.test_runner_proc.join(10)
>         self.logger.debug("After join")
>+        mp = mpcontext.get_context()
>         if self.test_runner_proc.is_alive():
>             # This might leak a file handle from the queue
>             self.logger.warning("Forcibly terminating runner process")
>             self.test_runner_proc.terminate()
>+            self.logger.debug("After terminating runner process")
> 
>             # Multiprocessing queues are backed by operating system pipes. If
>             # the pipe in the child process had buffered data at the time of
>             # forced termination, the queue is no longer in a usable state
>             # (subsequent attempts to retrieve items may block indefinitely).
>             # Discard the potentially-corrupted queue and create a new one.
>+            self.logger.debug("Recreating command queue")
>+            self.command_queue.cancel_join_thread()
>             self.command_queue.close()
>-            self.command_queue = Queue()
>+            self.command_queue = mp.Queue()
>+            self.logger.debug("Recreating remote queue")
>+            self.remote_queue.cancel_join_thread()
>             self.remote_queue.close()
>-            self.remote_queue = Queue()
>+            self.remote_queue = mp.Queue()
>         else:
>             self.logger.debug("Runner process exited with code %i" % self.test_runner_proc.exitcode)
> 
>@@ -915,3 +927,6 @@ class ManagerGroup(object):
> 
>     def unexpected_count(self):
>         return sum(manager.unexpected_count for manager in self.pool)
>+
>+    def unexpected_pass_count(self):
>+        return sum(manager.unexpected_pass_count for manager in self.pool)
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/browsers/test_sauce.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/browsers/test_sauce.py
>index e1e18ec5e9cd..3245d125c534 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/browsers/test_sauce.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/browsers/test_sauce.py
>@@ -1,6 +1,7 @@
>+import logging
> import sys
>+from unittest import mock
> 
>-import mock
> import pytest
> 
> from os.path import join, dirname
>@@ -11,6 +12,8 @@ sauce = pytest.importorskip("wptrunner.browsers.sauce")
> 
> from wptserve.config import ConfigBuilder
> 
>+logger = logging.getLogger()
>+
> 
> def test_sauceconnect_success():
>     with mock.patch.object(sauce.SauceConnect, "upload_prerun_exec"),\
>@@ -29,7 +32,7 @@ def test_sauceconnect_success():
>             sauce_connect_binary="ddd",
>             sauce_connect_args=[])
> 
>-        with ConfigBuilder(browser_host="example.net") as env_config:
>+        with ConfigBuilder(logger, browser_host="example.net") as env_config:
>             sauce_connect(None, env_config)
>             with sauce_connect:
>                 pass
>@@ -59,7 +62,7 @@ def test_sauceconnect_failure_exit(readyfile, returncode):
>             sauce_connect_binary="ddd",
>             sauce_connect_args=[])
> 
>-        with ConfigBuilder(browser_host="example.net") as env_config:
>+        with ConfigBuilder(logger, browser_host="example.net") as env_config:
>             sauce_connect(None, env_config)
>             with pytest.raises(sauce.SauceException):
>                 with sauce_connect:
>@@ -88,7 +91,7 @@ def test_sauceconnect_cleanup():
>             sauce_connect_binary="ddd",
>             sauce_connect_args=[])
> 
>-        with ConfigBuilder(browser_host="example.net") as env_config:
>+        with ConfigBuilder(logger, browser_host="example.net") as env_config:
>             sauce_connect(None, env_config)
>             with sauce_connect:
>                 Popen.return_value.poll.return_value = None
>@@ -112,7 +115,7 @@ def test_sauceconnect_failure_never_ready():
>             sauce_connect_binary="ddd",
>             sauce_connect_args=[])
> 
>-        with ConfigBuilder(browser_host="example.net") as env_config:
>+        with ConfigBuilder(logger, browser_host="example.net") as env_config:
>             sauce_connect(None, env_config)
>             with pytest.raises(sauce.SauceException):
>                 with sauce_connect:
>@@ -141,7 +144,8 @@ def test_sauceconnect_tunnel_domains():
>             sauce_connect_binary="ddd",
>             sauce_connect_args=[])
> 
>-        with ConfigBuilder(browser_host="example.net",
>+        with ConfigBuilder(logger,
>+                           browser_host="example.net",
>                            alternate_hosts={"alt": "example.org"},
>                            subdomains={"a", "b"},
>                            not_subdomains={"x", "y"}) as env_config:
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/browsers/test_webkitgtk.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/browsers/test_webkitgtk.py
>index 6150d50acf93..b20d3576674e 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/browsers/test_webkitgtk.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/browsers/test_webkitgtk.py
>@@ -1,3 +1,4 @@
>+import logging
> from os.path import join, dirname
> 
> import pytest
>@@ -9,6 +10,8 @@ from wptrunner import environment, products
> test_paths = {"/": {"tests_path": join(dirname(__file__), "..", "..", "..", "..", "..")}}  # repo root
> environment.do_delayed_imports(None, test_paths)
> 
>+logger = logging.getLogger()
>+
> 
> @active_products("product")
> def test_webkitgtk_certificate_domain_list(product):
>@@ -22,10 +25,7 @@ def test_webkitgtk_certificate_domain_list(product):
>     if product not in ["epiphany", "webkit", "webkitgtk_minibrowser"]:
>         pytest.skip("%s doesn't support certificate_domain_list" % product)
> 
>-    (check_args,
>-     target_browser_cls, get_browser_kwargs,
>-     executor_classes, get_executor_kwargs,
>-     env_options, get_env_extras, run_info_extras) = products.load_product({}, product)
>+    product_data = products.Product({}, product)
> 
>     cert_file = "/home/user/wpt/tools/certs/cacert.pem"
>     valid_domains_test = ["a.example.org", "b.example.org", "example.org",
>@@ -41,12 +41,25 @@ def test_webkitgtk_certificate_domain_list(product):
>     kwargs["webdriver_binary"] = None
>     kwargs["pause_after_test"] = False
>     kwargs["pause_on_unexpected"] = False
>-    with ConfigBuilder(browser_host="example.net",
>+    kwargs["debug_test"] = False
>+    with ConfigBuilder(logger,
>+                       browser_host="example.net",
>                        alternate_hosts={"alt": "example.org"},
>                        subdomains={"a", "b"},
>                        not_subdomains={"x", "y"}) as env_config:
> 
>-        executor_args = get_executor_kwargs(None, env_config, None, None, **kwargs)
>+        # We don't want to actually create a test environment; the get_executor_kwargs
>+        # function only really wants an object with the config key
>+
>+        class MockEnvironment:
>+            def __init__(self, config):
>+                self.config = config
>+
>+        executor_args = product_data.get_executor_kwargs(None,
>+                                                         None,
>+                                                         MockEnvironment(env_config),
>+                                                         {},
>+                                                         **kwargs)
>         assert('capabilities' in executor_args)
>         assert('webkitgtk:browserOptions' in executor_args['capabilities'])
>         assert('certificates' in executor_args['capabilities']['webkitgtk:browserOptions'])
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_formatters.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_formatters.py
>index 60b1b0a5a878..04526da702ba 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_formatters.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_formatters.py
>@@ -1,12 +1,9 @@
> import json
> import time
>-from six.moves import cStringIO as StringIO
>-
>-import mock
>+from io import StringIO
> 
> from mozlog import handlers, structuredlog
> 
>-from ..formatters import wptreport
> from ..formatters.wptscreenshot import WptscreenshotFormatter
> from ..formatters.wptreport import WptreportFormatter
> 
>@@ -97,45 +94,6 @@ def test_wptreport_lone_surrogate(capfd):
>     assert subtest["message"] == u"\U0001F601 U+de0aU+d83d"
> 
> 
>-def test_wptreport_lone_surrogate_ucs2(capfd):
>-    # Since UCS4 is a superset of UCS2 we can meaningfully test the UCS2 code on a
>-    # UCS4 build, but not the reverse. However UCS2 is harder to handle and UCS4 is
>-    # the commonest (and sensible) configuration, so that's OK.
>-    output = StringIO()
>-    logger = structuredlog.StructuredLogger("test_a")
>-    logger.add_handler(handlers.StreamHandler(output, WptreportFormatter()))
>-
>-    with mock.patch.object(wptreport,
>-                           'surrogate_replacement',
>-                           wptreport.SurrogateReplacementUcs2()):
>-        # output a bunch of stuff
>-        logger.suite_start(["test-id-1"])  # no run_info arg!
>-        logger.test_start("test-id-1")
>-        logger.test_status("test-id-1",
>-                           subtest=u"Name with surrogate\uD800",
>-                           status="FAIL",
>-                           message=u"\U0001F601 \uDE0A\uD83D \uD83D\uDE0A")
>-        logger.test_end("test-id-1",
>-                        status="PASS",
>-                        message=u"\uDE0A\uD83D \uD83D\uDE0A \U0001F601")
>-        logger.suite_end()
>-
>-    # check nothing got output to stdout/stderr
>-    # (note that mozlog outputs exceptions during handling to stderr!)
>-    captured = capfd.readouterr()
>-    assert captured.out == ""
>-    assert captured.err == ""
>-
>-    # check the actual output of the formatter
>-    output.seek(0)
>-    output_obj = json.load(output)
>-    test = output_obj["results"][0]
>-    assert test["message"] == u"U+de0aU+d83d \U0001f60a \U0001F601"
>-    subtest = test["subtests"][0]
>-    assert subtest["name"] == u"Name with surrogateU+d800"
>-    assert subtest["message"] == u"\U0001F601 U+de0aU+d83d \U0001f60a"
>-
>-
> def test_wptreport_known_intermittent(capfd):
>     output = StringIO()
>     logger = structuredlog.StructuredLogger("test_a")
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_products.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_products.py
>index 5d2bcf075d0f..120c7e72c63f 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_products.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_products.py
>@@ -1,6 +1,6 @@
> from os.path import join, dirname
>+from unittest import mock
> 
>-import mock
> import pytest
> 
> from .base import all_products, active_products
>@@ -14,7 +14,7 @@ environment.do_delayed_imports(None, test_paths)
> @active_products("product")
> def test_load_active_product(product):
>     """test we can successfully load the product of the current testenv"""
>-    products.load_product({}, product)
>+    products.Product({}, product)
>     # test passes if it doesn't throw
> 
> 
>@@ -22,7 +22,7 @@ def test_load_active_product(product):
> def test_load_all_products(product):
>     """test every product either loads or throws ImportError"""
>     try:
>-        products.load_product({}, product)
>+        products.Product({}, product)
>     except ImportError:
>         pass
> 
>@@ -31,26 +31,24 @@ def test_load_all_products(product):
>     "sauce": pytest.mark.skip("needs env extras kwargs"),
> })
> def test_server_start_config(product):
>-    (check_args,
>-     target_browser_cls, get_browser_kwargs,
>-     executor_classes, get_executor_kwargs,
>-     env_options, get_env_extras, run_info_extras) = products.load_product({}, product)
>+    product_data = products.Product({}, product)
> 
>-    env_extras = get_env_extras()
>+    env_extras = product_data.get_env_extras()
> 
>     with mock.patch.object(environment.serve, "start") as start:
>         with environment.TestEnvironment(test_paths,
>                                          1,
>                                          False,
>+                                         False,
>                                          None,
>-                                         env_options,
>+                                         product_data.env_options,
>                                          {"type": "none"},
>                                          env_extras):
>             start.assert_called_once()
>             args = start.call_args
>-            config = args[0][0]
>-            if "server_host" in env_options:
>-                assert config["server_host"] == env_options["server_host"]
>+            config = args[0][1]
>+            if "server_host" in product_data.env_options:
>+                assert config["server_host"] == product_data.env_options["server_host"]
>             else:
>                 assert config["server_host"] == config["browser_host"]
>             assert isinstance(config["bind_address"], bool)
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_testloader.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_testloader.py
>index 394d2a00177b..77cd85b820d7 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_testloader.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_testloader.py
>@@ -1,5 +1,3 @@
>-from __future__ import unicode_literals
>-
> import os
> import sys
> import tempfile
>@@ -8,6 +6,7 @@ import pytest
> 
> from mozlog import structured
> from ..testloader import TestFilter as Filter, TestLoader as Loader
>+from ..testloader import read_include_from_file
> from .test_wpttest import make_mock_manifest
> 
> here = os.path.dirname(__file__)
>@@ -58,6 +57,28 @@ def test_loader_h2_tests():
>     assert len(loader.disabled_tests["testharness"]) == 1
>     assert loader.disabled_tests["testharness"][0].url == "/a/bar.h2.html"
> 
>+@pytest.mark.xfail(sys.platform == "win32",
>+                   reason="NamedTemporaryFile cannot be reopened on Win32")
>+def test_include_file():
>+    test_cases = """
>+# This is a comment
>+/foo/bar-error.https.html
>+/foo/bar-success.https.html
>+/foo/idlharness.https.any.html
>+/foo/idlharness.https.any.worker.html
>+    """
>+
>+    with tempfile.NamedTemporaryFile(mode="wt") as f:
>+        f.write(test_cases)
>+        f.flush()
>+
>+        include = read_include_from_file(f.name)
>+
>+        assert len(include) == 4
>+        assert "/foo/bar-error.https.html" in include
>+        assert "/foo/bar-success.https.html" in include
>+        assert "/foo/idlharness.https.any.html" in include
>+        assert "/foo/idlharness.https.any.worker.html" in include
> 
> @pytest.mark.xfail(sys.platform == "win32",
>                    reason="NamedTemporaryFile cannot be reopened on Win32")
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_update.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_update.py
>index a1ba8de28780..804f75125180 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_update.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_update.py
>@@ -1,11 +1,12 @@
> import json
>-import mock
> import os
>-import pytest
> import sys
> from io import BytesIO
>+from unittest import mock
>+
>+import pytest
> 
>-from .. import metadata, manifestupdate
>+from .. import metadata, manifestupdate, wptmanifest
> from ..update.update import WPTUpdate
> from ..update.base import StepRunner, Step
> from mozlog import structuredlog, handlers, formatters
>@@ -442,7 +443,7 @@ def test_update_reorder_expected():
> 
>     assert not new_manifest.is_empty
>     assert new_manifest.get_test(test_id).children[0].get(
>-        "expected", default_run_info) == ["FAIL", "PASS"]
>+        "expected", default_run_info) == ["PASS", "FAIL"]
> 
> 
> def test_update_and_preserve_unchanged_expected_intermittent():
>@@ -1672,3 +1673,105 @@ def test_update_pickle():
>     wptupdate = WPTUpdate(logger, **args2)
>     wptupdate = WPTUpdate(logger, runner_cls=UpdateRunner, **args)
>     wptupdate.run()
>+
>+
>+def test_update_serialize_quoted():
>+    tests = [("path/to/test.htm", [test_id], "testharness",
>+              b"""[test.htm]
>+  expected: "ERROR"
>+  [test1]
>+    expected:
>+     if os == "linux": ["PASS", "FAIL"]
>+     "ERROR"
>+""")]
>+
>+    log_0 = suite_log([("test_start", {"test": test_id}),
>+                       ("test_status", {"test": test_id,
>+                                        "subtest": "test1",
>+                                        "status": "PASS",
>+                                        "known_intermittent": ["FAIL"]}),
>+                       ("test_end", {"test": test_id,
>+                                     "expected": "ERROR",
>+                                     "status": "OK"})],
>+                      run_info={"os": "linux"})
>+    log_1 = suite_log([("test_start", {"test": test_id}),
>+                       ("test_status", {"test": test_id,
>+                                        "subtest": "test1",
>+                                        "status": "FAIL",
>+                                        "expected": "PASS",
>+                                        "known_intermittent": ["FAIL"]}),
>+                       ("test_end", {"test": test_id,
>+                                     "expected": "ERROR",
>+                                     "status": "OK"})],
>+                      run_info={"os": "linux"})
>+    log_2 = suite_log([("test_start", {"test": test_id}),
>+                       ("test_status", {"test": test_id,
>+                                        "subtest": "test1",
>+                                        "status": "ERROR"}),
>+                       ("test_end", {"test": test_id,
>+                                     "expected": "ERROR",
>+                                     "status": "OK"})],
>+                      run_info={"os": "win"})
>+
>+    updated = update(tests, log_0, log_1, log_2, full_update=True, update_intermittent=True)
>+
>+
>+    manifest_str = wptmanifest.serialize(updated[0][1].node,
>+                                         skip_empty_data=True)
>+    assert manifest_str == """[test.htm]
>+  [test1]
>+    expected:
>+      if os == "linux": [PASS, FAIL]
>+      ERROR
>+"""
>+
>+
>+def test_update_serialize_unquoted():
>+    tests = [("path/to/test.htm", [test_id], "testharness",
>+              b"""[test.htm]
>+  expected: ERROR
>+  [test1]
>+    expected:
>+     if os == "linux": [PASS, FAIL]
>+     ERROR
>+""")]
>+
>+    log_0 = suite_log([("test_start", {"test": test_id}),
>+                       ("test_status", {"test": test_id,
>+                                        "subtest": "test1",
>+                                        "status": "PASS",
>+                                        "known_intermittent": ["FAIL"]}),
>+                       ("test_end", {"test": test_id,
>+                                     "expected": "ERROR",
>+                                     "status": "OK"})],
>+                      run_info={"os": "linux"})
>+    log_1 = suite_log([("test_start", {"test": test_id}),
>+                       ("test_status", {"test": test_id,
>+                                        "subtest": "test1",
>+                                        "status": "FAIL",
>+                                        "expected": "PASS",
>+                                        "known_intermittent": ["FAIL"]}),
>+                       ("test_end", {"test": test_id,
>+                                     "expected": "ERROR",
>+                                     "status": "OK"})],
>+                      run_info={"os": "linux"})
>+    log_2 = suite_log([("test_start", {"test": test_id}),
>+                       ("test_status", {"test": test_id,
>+                                        "subtest": "test1",
>+                                        "status": "ERROR"}),
>+                       ("test_end", {"test": test_id,
>+                                     "expected": "ERROR",
>+                                     "status": "OK"})],
>+                      run_info={"os": "win"})
>+
>+    updated = update(tests, log_0, log_1, log_2, full_update=True, update_intermittent=True)
>+
>+
>+    manifest_str = wptmanifest.serialize(updated[0][1].node,
>+                                         skip_empty_data=True)
>+    assert manifest_str == """[test.htm]
>+  [test1]
>+    expected:
>+      if os == "linux": [PASS, FAIL]
>+      ERROR
>+"""
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_wpttest.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_wpttest.py
>index 4eee9ccb1b69..59aa636a9037 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_wpttest.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/tests/test_wpttest.py
>@@ -1,5 +1,5 @@
>-import mock
> from io import BytesIO
>+from unittest import mock
> 
> from manifest import manifest as wptmanifest
> from manifest.item import TestharnessTest, RefTest
>@@ -202,14 +202,16 @@ def test_expect_any_subtest_status():
> 
> 
> def test_metadata_fuzzy():
>-    item = RefTest(".", "a/fuzzy.html", "/", "a/fuzzy.html",
>+    item = RefTest(tests_root=".",
>+                   path="a/fuzzy.html",
>+                   url_base="/",
>+                   url="a/fuzzy.html",
>                    references=[["/a/fuzzy-ref.html", "=="]],
>                    fuzzy=[[["/a/fuzzy.html", '/a/fuzzy-ref.html', '=='],
>                            [[2, 3], [10, 15]]]])
>     s = mock.Mock(rel_path="a/fuzzy.html", rel_path_parts=("a", "fuzzy.html"), hash="0"*40)
>     s.manifest_items = mock.Mock(return_value=(item.item_type, [item]))
> 
>-
>     manifest = wptmanifest.Manifest("")
> 
>     tree, sourcefile_mock = tree_and_sourcefile_mocks([(s, None, True)])
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/base.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/base.py
>index 547808e52933..47ea7ffb41f0 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/base.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/base.py
>@@ -1,9 +1,11 @@
>+from typing import ClassVar, List, Type
>+
> exit_unclean = object()
> exit_clean = object()
> 
> 
> class Step(object):
>-    provides = []
>+    provides = []  # type: ClassVar[List[str]]
> 
>     def __init__(self, logger):
>         self.logger = logger
>@@ -45,7 +47,7 @@ class Step(object):
> 
> 
> class StepRunner(object):
>-    steps = []
>+    steps = []  # type: ClassVar[List[Type[Step]]]
> 
>     def __init__(self, logger, state):
>         """Class that runs a specified series of Steps with a common State"""
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/state.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/state.py
>index bdb23fed99e1..a526c24c959f 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/state.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/state.py
>@@ -1,5 +1,5 @@
> import os
>-from six.moves import cPickle as pickle  # noqa: N813
>+import pickle
> 
> here = os.path.abspath(os.path.dirname(__file__))
> 
>@@ -97,7 +97,7 @@ class SavedState(BaseState):
>         try:
>             if not os.path.isfile(cls.filename):
>                 return None
>-            with open(cls.filename) as f:
>+            with open(cls.filename, "rb") as f:
>                 try:
>                     rv = pickle.load(f)
>                     logger.debug("Loading data %r" % (rv._data,))
>@@ -111,7 +111,7 @@ class SavedState(BaseState):
> 
>     def save(self):
>         """Write the state to disk"""
>-        with open(self.filename, "w") as f:
>+        with open(self.filename, "wb") as f:
>             pickle.dump(self, f)
> 
>     def clear(self):
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/sync.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/sync.py
>index f878752f4514..2c9834c672d6 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/sync.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/sync.py
>@@ -67,7 +67,7 @@ class UpdateCheckout(Step):
>                          state.local_branch)
>         sync_path = os.path.abspath(sync_tree.root)
>         if sync_path not in sys.path:
>-            from update import setup_paths
>+            from .update import setup_paths
>             setup_paths(sync_path)
> 
>     def restore(self, state):
>@@ -98,7 +98,7 @@ class UpdateManifest(Step):
>     provides = ["manifest_path", "test_manifest"]
> 
>     def create(self, state):
>-        from manifest import manifest
>+        from manifest import manifest  # type: ignore
>         state.manifest_path = os.path.join(state.metadata_path, "MANIFEST.json")
>         state.test_manifest = manifest.load_and_update(state.sync["path"],
>                                                        state.manifest_path,
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/tree.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/tree.py
>index f362770ff16d..2f43bacd15bf 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/tree.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/tree.py
>@@ -3,8 +3,6 @@ import re
> import subprocess
> import tempfile
> 
>-from six.moves import range
>-
> from .. import vcs
> from ..vcs import git, hg
> 
>@@ -87,7 +85,7 @@ class HgTree(object):
> 
>     @property
>     def is_clean(self):
>-        return self.hg("status").strip() == ""
>+        return self.hg("status").strip() == b""
> 
>     def add_new(self, prefix=None):
>         if prefix is not None:
>@@ -105,7 +103,7 @@ class HgTree(object):
>         except subprocess.CalledProcessError:
>             pass
> 
>-        patch_names = [item.strip() for item in self.hg("qseries").split("\n") if item.strip()]
>+        patch_names = [item.strip() for item in self.hg("qseries").split(b"\n") if item.strip()]
> 
>         suffix = 0
>         test_name = patch_name
>@@ -142,7 +140,7 @@ class GitTree(object):
> 
>     def __init__(self, root=None, log_error=True):
>         if root is None:
>-            root = git("rev-parse", "--show-toplevel", log_error=log_error).strip()
>+            root = git("rev-parse", "--show-toplevel", log_error=log_error).strip().decode('utf-8')
>         self.root = root
>         self.git = vcs.bind_to_repo(git, self.root, log_error=log_error)
>         self.message = None
>@@ -178,7 +176,7 @@ class GitTree(object):
> 
>     @property
>     def is_clean(self):
>-        return self.git("status").strip() == ""
>+        return self.git("status").strip() == b""
> 
>     def add_new(self, prefix=None):
>         """Add files to the staging area.
>@@ -203,7 +201,7 @@ class GitTree(object):
>             f.seek(0)
>             ignored_files = sync_tree.git("check-ignore", "--no-index", "--stdin", "-z", stdin=f)
>         args = []
>-        for entry in ignored_files.split('\0'):
>+        for entry in ignored_files.decode('utf-8').split('\0'):
>             args.append(os.path.join(prefix, entry))
>         if args:
>             self.git("add", "--force", *args)
>@@ -219,7 +217,7 @@ class GitTree(object):
>             args.append(ref_filter)
>         data = self.git("show-ref", *args)
>         rv = []
>-        for line in data.split("\n"):
>+        for line in data.split(b"\n"):
>             if not line.strip():
>                 continue
>             sha1, ref = line.split()
>@@ -237,7 +235,7 @@ class GitTree(object):
>             args.append(ref_filter)
>         data = self.git("ls-remote", remote, *args)
>         rv = []
>-        for line in data.split("\n"):
>+        for line in data.split(b"\n"):
>             if not line.strip():
>                 continue
>             sha1, ref = line.split()
>@@ -250,8 +248,8 @@ class GitTree(object):
>         :param remote: the remote URL
>         :param branch: the branch name"""
>         for sha1, ref in self.list_remote(remote, branch):
>-            if ref == "refs/heads/%s" % branch:
>-                return self.commit_cls(self, sha1)
>+            if ref.decode('utf-8') == "refs/heads/%s" % branch:
>+                return self.commit_cls(self, sha1.decode('utf-8'))
>         assert False
> 
>     def create_patch(self, patch_name, message):
>@@ -299,8 +297,8 @@ class GitTree(object):
> 
>         args = []
>         if branch:
>-            branches = [ref[len("refs/heads/"):] for sha1, ref in self.list_refs()
>-                        if ref.startswith("refs/heads/")]
>+            branches = [ref[len("refs/heads/"):].decode('utf-8') for sha1, ref in self.list_refs()
>+                        if ref.startswith(b"refs/heads/")]
>             branch = get_unique_name(branches, branch)
> 
>             args += ["-b", branch]
>@@ -336,8 +334,8 @@ class GitTree(object):
>         rv = []
> 
>         for repo_path in repo_paths:
>-            paths = vcs.git("ls-tree", "-r", "--name-only", "HEAD", repo=repo_path).split("\n")
>-            rv.extend(os.path.relpath(os.path.join(repo_path, item), self.root) for item in paths
>+            paths = vcs.git("ls-tree", "-r", "--name-only", "HEAD", repo=repo_path).split(b"\n")
>+            rv.extend(os.path.relpath(os.path.join(repo_path, item.decode('utf-8')), self.root) for item in paths
>                       if item.strip())
>         return rv
> 
>@@ -345,11 +343,11 @@ class GitTree(object):
>         """List submodule directories"""
>         output = self.git("submodule", "status", "--recursive")
>         rv = []
>-        for line in output.split("\n"):
>+        for line in output.split(b"\n"):
>             line = line.strip()
>             if not line:
>                 continue
>-            parts = line.split(" ")
>+            parts = line.split(b" ")
>             rv.append(parts[1])
>         return rv
> 
>@@ -403,5 +401,5 @@ class Commit(object):
>         self.git = self.tree.git
> 
>     def _get_meta(self):
>-        author, email, message = self.git("show", "-s", "--format=format:%an\n%ae\n%B", self.sha1).split("\n", 2)
>+        author, email, message = self.git("show", "-s", "--format=format:%an\n%ae\n%B", self.sha1).decode('utf-8').split("\n", 2)
>         return author, email, self.msg_cls(message)
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/update.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/update.py
>index 80e509dd383b..265a3311beb1 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/update.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/update/update.py
>@@ -1,8 +1,6 @@
> import os
> import sys
> 
>-from six import itervalues
>-
> from .metadata import MetadataUpdateRunner
> from .sync import SyncFromUpstreamRunner
> from .tree import GitTree, HgTree, NoVCSTree
>@@ -111,7 +109,7 @@ class RemoveObsolete(Step):
>         state.tests_path = state.paths["/"]["tests_path"]
>         state.metadata_path = state.paths["/"]["metadata_path"]
> 
>-        for url_paths in itervalues(paths):
>+        for url_paths in paths.values():
>             tests_path = url_paths["tests_path"]
>             metadata_path = url_paths["metadata_path"]
>             for dirpath, dirnames, filenames in os.walk(metadata_path):
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/vcs.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/vcs.py
>index 896d8a0d2c6e..3419a507dbae 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/vcs.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/vcs.py
>@@ -1,5 +1,6 @@
> import subprocess
> from functools import partial
>+from typing import Callable
> 
> from mozlog import get_default_logger
> 
>@@ -7,7 +8,7 @@ from wptserve.utils import isomorphic_decode
> 
> logger = None
> 
>-def vcs(bin_name):
>+def vcs(bin_name: str) -> Callable[..., None]:
>     def inner(command, *args, **kwargs):
>         global logger
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/webdriver_server.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/webdriver_server.py
>index dfae057fd332..565e3d4e43be 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/webdriver_server.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/webdriver_server.py
>@@ -5,14 +5,15 @@ import platform
> import socket
> import time
> import traceback
>+from typing import ClassVar, Type
> 
> import mozprocess
> 
>-from .process import cast_env
>+from .browsers.base import OutputHandler
> 
> 
> __all__ = ["SeleniumServer", "ChromeDriverServer", "CWTChromeDriverServer",
>-           "EdgeChromiumDriverServer", "OperaDriverServer", "GeckoDriverServer",
>+           "EdgeChromiumDriverServer", "OperaDriverServer",
>            "InternetExplorerDriverServer", "EdgeDriverServer",
>            "ServoDriverServer", "WebKitDriverServer", "WebDriverServer"]
> 
>@@ -21,6 +22,7 @@ class WebDriverServer(object):
>     __metaclass__ = abc.ABCMeta
> 
>     default_base_path = "/"
>+    output_handler_cls = OutputHandler  # type: ClassVar[Type[OutputHandler]]
> 
>     def __init__(self, logger, binary, host="127.0.0.1", port=None,
>                  base_path="", env=None, args=None):
>@@ -31,12 +33,14 @@ class WebDriverServer(object):
>         self.logger = logger
>         self.binary = binary
>         self.host = host
>+
>         if base_path == "":
>             self.base_path = self.default_base_path
>         else:
>             self.base_path = base_path
>         self.env = os.environ.copy() if env is None else env
> 
>+        self._output_handler = None
>         self._port = port
>         self._cmd = None
>         self._args = args if args is not None else []
>@@ -46,18 +50,28 @@ class WebDriverServer(object):
>     def make_command(self):
>         """Returns the full command for starting the server process as a list."""
> 
>-    def start(self, block=False):
>+    def start(self,
>+              block=False,
>+              output_handler_kwargs=None,
>+              output_handler_start_kwargs=None):
>         try:
>-            self._run(block)
>+            self._run(block, output_handler_kwargs, output_handler_start_kwargs)
>         except KeyboardInterrupt:
>             self.stop()
> 
>-    def _run(self, block):
>+    def _run(self, block, output_handler_kwargs, output_handler_start_kwargs):
>+        if output_handler_kwargs is None:
>+            output_handler_kwargs = {}
>+        if output_handler_start_kwargs is None:
>+            output_handler_start_kwargs = {}
>         self._cmd = self.make_command()
>+        self._output_handler = self.output_handler_cls(self.logger,
>+                                                       self._cmd,
>+                                                       **output_handler_kwargs)
>         self._proc = mozprocess.ProcessHandler(
>             self._cmd,
>-            processOutputLine=self.on_output,
>-            env=cast_env(self.env),
>+            processOutputLine=self._output_handler,
>+            env=self.env,
>             storeOutput=False)
> 
>         self.logger.debug("Starting WebDriver: %s" % ' '.join(self._cmd))
>@@ -68,6 +82,7 @@ class WebDriverServer(object):
>                 raise IOError(
>                     "WebDriver executable not found: %s" % self.binary)
>             raise
>+        self._output_handler.after_process_start(self._proc.pid)
> 
>         self.logger.debug(
>             "Waiting for WebDriver to become accessible: %s" % self.url)
>@@ -78,27 +93,28 @@ class WebDriverServer(object):
>                 "WebDriver was not accessible "
>                 "within the timeout:\n%s" % traceback.format_exc())
>             raise
>-
>+        self._output_handler.start(**output_handler_start_kwargs)
>         if block:
>             self._proc.wait()
> 
>     def stop(self, force=False):
>         self.logger.debug("Stopping WebDriver")
>+        clean = True
>         if self.is_alive():
>             kill_result = self._proc.kill()
>             if force and kill_result != 0:
>-                return self._proc.kill(9)
>-            return kill_result
>-        return not self.is_alive()
>+                clean = False
>+                self._proc.kill(9)
>+        success = not self.is_alive()
>+        if success and self._output_handler is not None:
>+            # Only try to do output post-processing if we managed to shut down
>+            self._output_handler.after_process_stop(clean)
>+            self._output_handler = None
>+        return success
> 
>     def is_alive(self):
>         return hasattr(self._proc, "proc") and self._proc.poll() is None
> 
>-    def on_output(self, line):
>-        self.logger.process_output(self.pid,
>-                                   line.decode("utf8", "replace"),
>-                                   command=" ".join(self._cmd))
>-
>     @property
>     def pid(self):
>         if self._proc is not None:
>@@ -123,88 +139,42 @@ class SeleniumServer(WebDriverServer):
> 
> 
> class ChromeDriverServer(WebDriverServer):
>-    def __init__(self, logger, binary="chromedriver", port=None,
>-                 base_path="", args=None):
>-        WebDriverServer.__init__(
>-            self, logger, binary, port=port, base_path=base_path, args=args)
>-
>     def make_command(self):
>         return [self.binary,
>                 cmd_arg("port", str(self.port)),
>                 cmd_arg("url-base", self.base_path) if self.base_path else "",
>                 cmd_arg("enable-chrome-logs")] + self._args
> 
>-class CWTChromeDriverServer(WebDriverServer):
>-    def __init__(self, logger, binary, port=None, args=None):
>-        WebDriverServer.__init__(self, logger, binary, port=port, args=args)
> 
>+class CWTChromeDriverServer(WebDriverServer):
>     def make_command(self):
>         return [self.binary,
>                 "--port=%s" % str(self.port)] + self._args
> 
>-class EdgeChromiumDriverServer(WebDriverServer):
>-    def __init__(self, logger, binary="msedgedriver", port=None,
>-                 base_path="", args=None):
>-        WebDriverServer.__init__(
>-            self, logger, binary, port=port, base_path=base_path, args=args)
> 
>+class EdgeChromiumDriverServer(WebDriverServer):
>     def make_command(self):
>         return [self.binary,
>                 cmd_arg("port", str(self.port)),
>                 cmd_arg("url-base", self.base_path) if self.base_path else ""] + self._args
> 
>-class EdgeDriverServer(WebDriverServer):
>-    def __init__(self, logger, binary="microsoftwebdriver.exe", port=None,
>-                 base_path="", host="localhost", args=None):
>-        WebDriverServer.__init__(
>-            self, logger, binary, host=host, port=port, args=args)
> 
>+class EdgeDriverServer(WebDriverServer):
>     def make_command(self):
>         return [self.binary,
>                 "--port=%s" % str(self.port)] + self._args
> 
>-class OperaDriverServer(ChromeDriverServer):
>-    def __init__(self, logger, binary="operadriver", port=None,
>-                 base_path="", args=None):
>-        ChromeDriverServer.__init__(
>-            self, logger, binary, port=port, base_path=base_path, args=args)
> 
>+class OperaDriverServer(ChromeDriverServer):
>+    pass
> 
> class InternetExplorerDriverServer(WebDriverServer):
>-    def __init__(self, logger, binary="IEDriverServer.exe", port=None,
>-                 base_path="", host="localhost", args=None):
>-        WebDriverServer.__init__(
>-            self, logger, binary, host=host, port=port, args=args)
>-
>     def make_command(self):
>         return [self.binary,
>                 "--port=%s" % str(self.port)] + self._args
> 
> 
>-class GeckoDriverServer(WebDriverServer):
>-    def __init__(self, logger, marionette_port=2828, binary="geckodriver",
>-                 host="127.0.0.1", port=None, args=None):
>-        env = os.environ.copy()
>-        env["RUST_BACKTRACE"] = "1"
>-        WebDriverServer.__init__(self, logger, binary,
>-                                 host=host,
>-                                 port=port,
>-                                 env=cast_env(env),
>-                                 args=args)
>-        self.marionette_port = marionette_port
>-
>-    def make_command(self):
>-        return [self.binary,
>-                "--marionette-port", str(self.marionette_port),
>-                "--host", self.host,
>-                "--port", str(self.port)] + self._args
>-
>-
> class SafariDriverServer(WebDriverServer):
>-    def __init__(self, logger, binary="safaridriver", port=None, args=None):
>-        WebDriverServer.__init__(
>-            self, logger, binary, port=port, args=args)
>-
>     def make_command(self):
>         return [self.binary,
>                 "--port=%s" % str(self.port)] + self._args
>@@ -212,13 +182,13 @@ class SafariDriverServer(WebDriverServer):
> 
> class ServoDriverServer(WebDriverServer):
>     def __init__(self, logger, binary="servo", binary_args=None, host="127.0.0.1",
>-                 port=None, args=None):
>-        env = os.environ.copy()
>+                 port=None, env=None, args=None):
>+        env = env if env is not None else os.environ.copy()
>         env["RUST_BACKTRACE"] = "1"
>         WebDriverServer.__init__(self, logger, binary,
>                                  host=host,
>                                  port=port,
>-                                 env=cast_env(env),
>+                                 env=env,
>                                  args=args)
>         self.binary_args = binary_args
> 
>@@ -233,9 +203,6 @@ class ServoDriverServer(WebDriverServer):
> 
> 
> class WebKitDriverServer(WebDriverServer):
>-    def __init__(self, logger, binary=None, port=None, args=None):
>-        WebDriverServer.__init__(self, logger, binary, port=port, args=args)
>-
>     def make_command(self):
>         return [self.binary, "--port=%s" % str(self.port)] + self._args
> 
>@@ -254,7 +221,7 @@ def get_free_port():
>         s = socket.socket()
>         try:
>             s.bind(("127.0.0.1", 0))
>-        except socket.error:
>+        except OSError:
>             continue
>         else:
>             return s.getsockname()[1]
>@@ -265,7 +232,7 @@ def get_free_port():
> def wait_for_service(addr, timeout=60):
>     """Waits until network service given as a tuple of (host, port) becomes
>     available or the `timeout` duration is reached, at which point
>-    ``socket.error`` is raised."""
>+    ``socket.timeout`` is raised."""
>     end = time.time() + timeout
>     while end > time.time():
>         so = socket.socket()
>@@ -273,7 +240,7 @@ def wait_for_service(addr, timeout=60):
>             so.connect(addr)
>         except socket.timeout:
>             pass
>-        except socket.error as e:
>+        except OSError as e:
>             if e.errno != errno.ECONNREFUSED:
>                 raise
>         else:
>@@ -281,4 +248,4 @@ def wait_for_service(addr, timeout=60):
>         finally:
>             so.close()
>         time.sleep(0.5)
>-    raise socket.error("Service is unavailable: %s:%i" % addr)
>+    raise socket.timeout("Service is unavailable: %s:%i" % addr)
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptcommandline.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptcommandline.py
>index 9d1d40480954..c7050eb80c2b 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptcommandline.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptcommandline.py
>@@ -1,11 +1,9 @@
>-from __future__ import absolute_import, print_function
> import argparse
> import os
> import sys
> from collections import OrderedDict
> from distutils.spawn import find_executable
> from datetime import timedelta
>-from six import ensure_text, iterkeys, itervalues, iteritems
> 
> from . import config
> from . import wpttest
>@@ -16,7 +14,7 @@ def abs_path(path):
> 
> 
> def url_or_path(path):
>-    from six.moves.urllib.parse import urlparse
>+    from urllib.parse import urlparse
> 
>     parsed = urlparse(path)
>     if len(parsed.scheme) > 2:
>@@ -72,6 +70,10 @@ scheme host and port.""")
>                         default=True,
>                         dest="fail_on_unexpected",
>                         help="Exit with status code 0 when test expectations are violated")
>+    parser.add_argument("--no-fail-on-unexpected-pass", action="store_false",
>+                        default=True,
>+                        dest="fail_on_unexpected_pass",
>+                        help="Exit with status code 0 when all unexpected results are PASS")
> 
>     mode_group = parser.add_argument_group("Mode")
>     mode_group.add_argument("--list-test-groups", action="store_true",
>@@ -131,6 +133,8 @@ scheme host and port.""")
>                                       help="Test types to run")
>     test_selection_group.add_argument("--include", action="append",
>                                       help="URL prefix to include")
>+    test_selection_group.add_argument("--include-file", action="store",
>+                                      help="A file listing URL prefix for tests")
>     test_selection_group.add_argument("--exclude", action="append",
>                                       help="URL prefix to exclude")
>     test_selection_group.add_argument("--include-manifest", type=abs_path,
>@@ -170,6 +174,8 @@ scheme host and port.""")
>                                  help="Halt the test runner after each test (this happens by default if only a single test is run)")
>     debugging_group.add_argument('--no-pause-after-test', dest="pause_after_test", action="store_false",
>                                  help="Don't halt the test runner irrespective of the number of tests run")
>+    debugging_group.add_argument('--debug-test', dest="debug_test", action="store_true",
>+                                 help="Run tests with additional debugging features enabled")
> 
>     debugging_group.add_argument('--pause-on-unexpected', action="store_true",
>                                  help="Halt the test runner when an unexpected result is encountered")
>@@ -181,7 +187,6 @@ scheme host and port.""")
>                                  help="Path or url to symbols file used to analyse crash minidumps.")
>     debugging_group.add_argument("--stackwalk-binary", action="store", type=abs_path,
>                                  help="Path to stackwalker program used to analyse minidumps.")
>-
>     debugging_group.add_argument("--pdb", action="store_true",
>                                  help="Drop into pdb on python exception")
> 
>@@ -196,6 +201,8 @@ scheme host and port.""")
>     config_group.add_argument('--webdriver-arg',
>                               default=[], action="append", dest="webdriver_args",
>                               help="Extra argument for the WebDriver binary")
>+    config_group.add_argument("--adb-binary", action="store",
>+                              help="Path to adb binary to use")
>     config_group.add_argument("--package-name", action="store",
>                               help="Android package name to run tests against")
>     config_group.add_argument("--device-serial", action="store",
>@@ -284,6 +291,8 @@ scheme host and port.""")
>                              help="Disable fission in Gecko.")
>     gecko_group.add_argument("--stackfix-dir", dest="stackfix_dir", action="store",
>                              help="Path to directory containing assertion stack fixing scripts")
>+    gecko_group.add_argument("--specialpowers-path", action="store",
>+                             help="Path to specialPowers extension xpi file")
>     gecko_group.add_argument("--setpref", dest="extra_prefs", action='append',
>                              default=[], metavar="PREF=VALUE",
>                              help="Defines an extra user preference (overrides those in prefs_root)")
>@@ -312,14 +321,17 @@ scheme host and port.""")
>                              default=[], action="append", dest="user_stylesheets",
>                              help="Inject a user CSS stylesheet into every test.")
> 
>-    servo_group = parser.add_argument_group("Chrome-specific")
>-    servo_group.add_argument("--enable-mojojs", action="store_true", default=False,
>+    chrome_group = parser.add_argument_group("Chrome-specific")
>+    chrome_group.add_argument("--enable-mojojs", action="store_true", default=False,
>                              help="Enable MojoJS for testing. Note that this flag is usally "
>                              "enabled automatically by `wpt run`, if it succeeds in downloading "
>                              "the right version of mojojs.zip or if --mojojs-path is specified.")
>-    servo_group.add_argument("--mojojs-path",
>+    chrome_group.add_argument("--mojojs-path",
>                              help="Path to mojojs gen/ directory. If it is not specified, `wpt run` "
>                              "will download and extract mojojs.zip into _venv2/mojojs/gen.")
>+    chrome_group.add_argument("--enable-swiftshader", action="store_true", default=False,
>+                             help="Enable SwiftShader for CPU-based 3D graphics. This can be used "
>+                             "in environments with no hardware GPU available.")
> 
>     sauce_group = parser.add_argument_group("Sauce Labs-specific")
>     sauce_group.add_argument("--sauce-browser", dest="sauce_browser",
>@@ -354,13 +366,17 @@ scheme host and port.""")
> 
>     taskcluster_group = parser.add_argument_group("Taskcluster-specific")
>     taskcluster_group.add_argument("--github-checks-text-file",
>-                                   type=ensure_text,
>+                                   type=str,
>                                    help="Path to GitHub checks output file")
> 
>     webkit_group = parser.add_argument_group("WebKit-specific")
>     webkit_group.add_argument("--webkit-port", dest="webkit_port",
>                               help="WebKit port")
> 
>+    safari_group = parser.add_argument_group("Safari-specific")
>+    safari_group.add_argument("--kill-safari", dest="kill_safari", action="store_true", default=False,
>+                              help="Kill Safari when stopping the browser")
>+
>     parser.add_argument("test_list", nargs="*",
>                         help="List of URLs for tests to run, or paths including tests to run. "
>                              "(equivalent to --include)")
>@@ -402,7 +418,7 @@ def set_from_config(kwargs):
>                     ("host_cert_path", "host_cert_path", True),
>                     ("host_key_path", "host_key_path", True)]}
> 
>-    for section, values in iteritems(keys):
>+    for section, values in keys.items():
>         for config_value, kw_value, is_path in values:
>             if kw_value in kwargs and kwargs[kw_value] is None:
>                 if not is_path:
>@@ -438,7 +454,7 @@ def get_test_paths(config):
>     # Set up test_paths
>     test_paths = OrderedDict()
> 
>-    for section in iterkeys(config):
>+    for section in config.keys():
>         if section.startswith("manifest:"):
>             manifest_opts = config.get(section)
>             url_base = manifest_opts.get("url_base", "/")
>@@ -464,7 +480,7 @@ def exe_path(name):
> 
> 
> def check_paths(kwargs):
>-    for test_paths in itervalues(kwargs["test_paths"]):
>+    for test_paths in kwargs["test_paths"].values():
>         if not ("tests_path" in test_paths and
>                 "metadata_path" in test_paths):
>             print("Fatal: must specify both a test path and metadata path")
>@@ -472,7 +488,7 @@ def check_paths(kwargs):
>         if "manifest_path" not in test_paths:
>             test_paths["manifest_path"] = os.path.join(test_paths["metadata_path"],
>                                                        "MANIFEST.json")
>-        for key, path in iteritems(test_paths):
>+        for key, path in test_paths.items():
>             name = key.split("_", 1)[0]
> 
>             if name == "manifest":
>@@ -588,7 +604,7 @@ def check_args(kwargs):
>         kwargs["reftest_internal"] = True
> 
>     if kwargs["reftest_screenshot"] is None:
>-        kwargs["reftest_screenshot"] = "unexpected"
>+        kwargs["reftest_screenshot"] = "unexpected" if not kwargs["debug_test"] else "always"
> 
>     if kwargs["enable_webrender"] is None:
>         kwargs["enable_webrender"] = False
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptlogging.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptlogging.py
>index 444d1d962d25..b5cb58881fd0 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptlogging.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptlogging.py
>@@ -1,4 +1,5 @@
> import logging
>+from threading import Thread
> 
> from mozlog import commandline, stdadapter, set_default_logger
> from mozlog.structuredlog import StructuredLogger, log_levels
>@@ -65,3 +66,42 @@ class LoggedAboveLevelHandler(object):
>             not self.has_log and
>             log_levels[data["level"]] <= self.min_level):
>             self.has_log = True
>+
>+
>+class QueueHandler(logging.Handler):
>+    def __init__(self, queue, level=logging.NOTSET):
>+        self.queue = queue
>+        logging.Handler.__init__(self, level=level)
>+
>+    def createLock(self):
>+        # The queue provides its own locking
>+        self.lock = None
>+
>+    def emit(self, record):
>+        msg = self.format(record)
>+        data = {"action": "log",
>+                "level": record.levelname,
>+                "thread": record.threadName,
>+                "pid": record.process,
>+                "source": self.name,
>+                "message": msg}
>+        self.queue.put(data)
>+
>+
>+class LogQueueThread(Thread):
>+    """Thread for handling log messages from a queue"""
>+    def __init__(self, queue, logger):
>+        self.queue = queue
>+        self.logger = logger
>+        super().__init__(name="Thread-Log")
>+
>+    def run(self):
>+        while True:
>+            try:
>+                data = self.queue.get()
>+            except (EOFError, IOError):
>+                break
>+            if data is None:
>+                # A None message is used to shut down the logging thread
>+                break
>+            self.logger.log_raw(data)
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/backends/conditional.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/backends/conditional.py
>index 3b11e83012ab..30dd1449156e 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/backends/conditional.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/backends/conditional.py
>@@ -1,5 +1,5 @@
> import operator
>-from six import ensure_text, iteritems, iterkeys, text_type
>+from six import ensure_text
> 
> from ..node import NodeVisitor, DataNode, ConditionalNode, KeyValueNode, ListNode, ValueNode, BinaryExpressionNode, VariableNode
> from ..parser import parse
>@@ -300,9 +300,9 @@ class ManifestItem(object):
>         if isinstance(value, list):
>             value_node = ListNode()
>             for item in value:
>-                value_node.append(ValueNode(text_type(item)))
>+                value_node.append(ValueNode(str(item)))
>         else:
>-            value_node = ValueNode(text_type(value))
>+            value_node = ValueNode(str(value))
>         if condition is not None:
>             if not isinstance(condition, ConditionalNode):
>                 conditional_node = ConditionalNode()
>@@ -368,17 +368,17 @@ class ManifestItem(object):
>     def _flatten(self):
>         rv = {}
>         for node in [self, self.root]:
>-            for name, value in iteritems(node._data):
>+            for name, value in node._data.items():
>                 if name not in rv:
>                     rv[name] = value
>         return rv
> 
>     def iteritems(self):
>-        for item in iteritems(self._flatten()):
>+        for item in self._flatten().items():
>             yield item
> 
>     def iterkeys(self):
>-        for item in iterkeys(self._flatten()):
>+        for item in self._flatten().keys():
>             yield item
> 
>     def iter_properties(self):
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/node.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/node.py
>index 0f82d7006b69..5e9d2b642744 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/node.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/node.py
>@@ -1,5 +1,3 @@
>-from six.moves import range
>-
> class NodeVisitor(object):
>     def visit(self, node):
>         # This is ugly as hell, but we don't have multimethods and
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/parser.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/parser.py
>index 911efac80f27..4c97c6914139 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/parser.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/parser.py
>@@ -12,10 +12,7 @@
> 
> # TODO: keep comments in the tree
> 
>-from __future__ import unicode_literals
>-
>-from six import binary_type, text_type, BytesIO, unichr
>-from six.moves import range
>+from io import BytesIO
> 
> from .node import (Node, AtomNode, BinaryExpressionNode, BinaryOperatorNode,
>                    ConditionalNode, DataNode, IndexNode, KeyValueNode, ListNode,
>@@ -50,7 +47,7 @@ atoms = {"True": True,
>          "Reset": object()}
> 
> def decode(s):
>-    assert isinstance(s, text_type)
>+    assert isinstance(s, str)
>     return s
> 
> 
>@@ -59,7 +56,7 @@ def precedence(operator_node):
> 
> 
> class TokenTypes(object):
>-    def __init__(self):
>+    def __init__(self) -> None:
>         for type in ["group_start", "group_end", "paren", "list_start", "list_end", "separator", "ident", "string", "number", "atom", "eof"]:
>             setattr(self, type, type)
> 
>@@ -79,7 +76,7 @@ class Tokenizer(object):
> 
>     def tokenize(self, stream):
>         self.reset()
>-        assert not isinstance(stream, text_type)
>+        assert not isinstance(stream, str)
>         if isinstance(stream, bytes):
>             stream = BytesIO(stream)
>         if not hasattr(stream, "name"):
>@@ -89,7 +86,7 @@ class Tokenizer(object):
> 
>         self.next_line_state = self.line_start_state
>         for i, line in enumerate(stream):
>-            assert isinstance(line, binary_type)
>+            assert isinstance(line, bytes)
>             self.state = self.next_line_state
>             assert self.state is not None
>             states = []
>@@ -97,7 +94,7 @@ class Tokenizer(object):
>             self.line_number = i + 1
>             self.index = 0
>             self.line = line.decode('utf-8').rstrip()
>-            assert isinstance(self.line, text_type)
>+            assert isinstance(self.line, str)
>             while self.state != self.eol_state:
>                 states.append(self.state)
>                 tokens = self.state()
>@@ -505,7 +502,7 @@ class Tokenizer(object):
>             value += self.escape_value(c)
>             self.consume()
> 
>-        return unichr(value)
>+        return chr(value)
> 
>     def escape_value(self, c):
>         if '0' <= c <= '9':
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/serializer.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/serializer.py
>index ec8d80ed6f71..e31a60791ea7 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/serializer.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/serializer.py
>@@ -1,4 +1,3 @@
>-from __future__ import unicode_literals
> from six import ensure_text
> 
> from .node import NodeVisitor, ValueNode, ListNode, BinaryExpressionNode
>@@ -34,6 +33,7 @@ class ManifestSerializer(NodeVisitor):
>         rv = "\n".join(self.visit(root))
>         if not rv:
>             return rv
>+        rv = rv.strip()
>         if rv[-1] != "\n":
>             rv = rv + "\n"
>         return rv
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/tests/test_serializer.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/tests/test_serializer.py
>index b247855801ea..02e52815dbdc 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/tests/test_serializer.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptmanifest/tests/test_serializer.py
>@@ -1,8 +1,5 @@
>-import sys
> import unittest
> 
>-import pytest
>-
> from .. import parser, serializer
> 
> 
>@@ -192,7 +189,6 @@ class TokenizerTest(unittest.TestCase):
>                      r"""key: "#"
> """)
> 
>-    @pytest.mark.xfail(sys.maxunicode == 0xFFFF, reason="narrow unicode")
>     def test_escape_9(self):
>         self.compare(br"""key: \U10FFFFabc""",
>                      u"""key: \U0010FFFFabc
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptrunner.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptrunner.py
>index e1d9ef8b1a91..25a2515ef6f8 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptrunner.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wptrunner.py
>@@ -1,15 +1,13 @@
>-from __future__ import print_function, unicode_literals
>-
> import json
> import os
> import sys
>-from six import iteritems, itervalues
> 
> import wptserve
> from wptserve import sslutils
> 
> from . import environment as env
> from . import instruments
>+from . import mpcontext
> from . import products
> from . import testloader
> from . import wptcommandline
>@@ -18,7 +16,6 @@ from . import wpttest
> from mozlog import capture, handlers
> from .font import FontInstaller
> from .testrunner import ManagerGroup
>-from .browsers.base import NullBrowser
> 
> here = os.path.dirname(__file__)
> 
>@@ -65,6 +62,9 @@ def get_loader(test_paths, product, debug=None, run_info_extras=None, chunker_kw
>     manifest_filters = []
> 
>     include = kwargs["include"]
>+    if kwargs["include_file"]:
>+        include = include or []
>+        include.extend(testloader.read_include_from_file(kwargs["include_file"]))
>     if test_groups:
>         include = testloader.update_include_for_groups(test_groups, include)
> 
>@@ -96,7 +96,7 @@ def get_loader(test_paths, product, debug=None, run_info_extras=None, chunker_kw
> def list_test_groups(test_paths, product, **kwargs):
>     env.do_delayed_imports(logger, test_paths)
> 
>-    run_info_extras = products.load_product(kwargs["config"], product)[-1](**kwargs)
>+    run_info_extras = products.Product(kwargs["config"], product).run_info_extras(**kwargs)
> 
>     run_info, test_loader = get_loader(test_paths, product,
>                                        run_info_extras=run_info_extras, **kwargs)
>@@ -110,12 +110,12 @@ def list_disabled(test_paths, product, **kwargs):
> 
>     rv = []
> 
>-    run_info_extras = products.load_product(kwargs["config"], product)[-1](**kwargs)
>+    run_info_extras = products.Product(kwargs["config"], product).run_info_extras(**kwargs)
> 
>     run_info, test_loader = get_loader(test_paths, product,
>                                        run_info_extras=run_info_extras, **kwargs)
> 
>-    for test_type, tests in iteritems(test_loader.disabled_tests):
>+    for test_type, tests in test_loader.disabled_tests.items():
>         for test in tests:
>             rv.append({"test": test.id, "reason": test.disabled()})
>     print(json.dumps(rv, indent=2))
>@@ -124,7 +124,7 @@ def list_disabled(test_paths, product, **kwargs):
> def list_tests(test_paths, product, **kwargs):
>     env.do_delayed_imports(logger, test_paths)
> 
>-    run_info_extras = products.load_product(kwargs["config"], product)[-1](**kwargs)
>+    run_info_extras = products.Product(kwargs["config"], product).run_info_extras(**kwargs)
> 
>     run_info, test_loader = get_loader(test_paths, product,
>                                        run_info_extras=run_info_extras, **kwargs)
>@@ -139,8 +139,10 @@ def get_pause_after_test(test_loader, **kwargs):
>             return False
>         if kwargs["headless"]:
>             return False
>+        if kwargs["debug_test"]:
>+            return True
>         tests = test_loader.tests
>-        is_single_testharness = (sum(len(item) for item in itervalues(tests)) == 1 and
>+        is_single_testharness = (sum(len(item) for item in tests.values()) == 1 and
>                                  len(tests.get("testharness", [])) == 1)
>         if kwargs["repeat"] == 1 and kwargs["rerun"] == 1 and is_single_testharness:
>             return True
>@@ -151,15 +153,18 @@ def get_pause_after_test(test_loader, **kwargs):
> def run_tests(config, test_paths, product, **kwargs):
>     """Set up the test environment, load the list of tests to be executed, and
>     invoke the remainder of the code to execute tests"""
>+    mp = mpcontext.get_context()
>     if kwargs["instrument_to_file"] is None:
>         recorder = instruments.NullInstrument()
>     else:
>         recorder = instruments.Instrument(kwargs["instrument_to_file"])
>-    with recorder as recording, capture.CaptureIO(logger, not kwargs["no_capture_stdio"]):
>+    with recorder as recording, capture.CaptureIO(logger,
>+                                                  not kwargs["no_capture_stdio"],
>+                                                  mp_context=mp):
>         recording.set(["startup"])
>         env.do_delayed_imports(logger, test_paths)
> 
>-        product = products.load_product(config, product, load_cls=True)
>+        product = products.Product(config, product)
> 
>         env_extras = product.get_env_extras(**kwargs)
> 
>@@ -194,6 +199,7 @@ def run_tests(config, test_paths, product, **kwargs):
>         skipped_tests = 0
>         test_total = 0
>         unexpected_total = 0
>+        unexpected_pass_total = 0
> 
>         if len(test_loader.test_ids) == 0 and kwargs["test_list"]:
>             logger.critical("Unable to find any tests at the path(s):")
>@@ -219,6 +225,7 @@ def run_tests(config, test_paths, product, **kwargs):
>         with env.TestEnvironment(test_paths,
>                                  testharness_timeout_multipler,
>                                  kwargs["pause_after_test"],
>+                                 kwargs["debug_test"],
>                                  kwargs["debug_info"],
>                                  product.env_options,
>                                  ssl_config,
>@@ -229,7 +236,7 @@ def run_tests(config, test_paths, product, **kwargs):
>             try:
>                 test_environment.ensure_started()
>             except env.TestEnvironmentError as e:
>-                logger.critical("Error starting test environment: %s" % e.message)
>+                logger.critical("Error starting test environment: %s" % e)
>                 raise
> 
>             recording.set(["startup"])
>@@ -247,6 +254,7 @@ def run_tests(config, test_paths, product, **kwargs):
> 
>                 test_count = 0
>                 unexpected_count = 0
>+                unexpected_pass_count = 0
> 
>                 tests = []
>                 for test_type in test_loader.test_types:
>@@ -265,25 +273,19 @@ def run_tests(config, test_paths, product, **kwargs):
>                 for test_type in kwargs["test_types"]:
>                     logger.info("Running %s tests" % test_type)
> 
>-                    # WebDriver tests may create and destroy multiple browser
>-                    # processes as part of their expected behavior. These
>-                    # processes are managed by a WebDriver server binary. This
>-                    # obviates the need for wptrunner to provide a browser, so
>-                    # the NullBrowser is used in place of the "target" browser
>-                    if test_type == "wdspec":
>-                        browser_cls = NullBrowser
>-                    else:
>-                        browser_cls = product.browser_cls
>+                    browser_cls = product.get_browser_cls(test_type)
> 
>-                    browser_kwargs = product.get_browser_kwargs(test_type,
>+                    browser_kwargs = product.get_browser_kwargs(logger,
>+                                                                test_type,
>                                                                 run_info,
>                                                                 config=test_environment.config,
>+                                                                num_test_groups=len(test_groups),
>                                                                 **kwargs)
> 
>                     executor_cls = product.executor_classes.get(test_type)
>-                    executor_kwargs = product.get_executor_kwargs(test_type,
>-                                                                  test_environment.config,
>-                                                                  test_environment.cache_manager,
>+                    executor_kwargs = product.get_executor_kwargs(logger,
>+                                                                  test_type,
>+                                                                  test_environment,
>                                                                   run_info,
>                                                                   **kwargs)
> 
>@@ -334,10 +336,13 @@ def run_tests(config, test_paths, product, **kwargs):
>                             raise
>                         test_count += manager_group.test_count()
>                         unexpected_count += manager_group.unexpected_count()
>+                        unexpected_pass_count += manager_group.unexpected_pass_count()
>                 recording.set(["after-end"])
>                 test_total += test_count
>                 unexpected_total += unexpected_count
>-                logger.info("Got %i unexpected results" % unexpected_count)
>+                unexpected_pass_total += unexpected_pass_count
>+                logger.info("Got %i unexpected results, with %i unexpected passes" %
>+                            (unexpected_count, unexpected_pass_count))
>                 logger.suite_end()
>                 if repeat_until_unexpected and unexpected_total > 0:
>                     break
>@@ -359,6 +364,13 @@ def run_tests(config, test_paths, product, **kwargs):
>         logger.info("Tolerating %s unexpected results" % unexpected_total)
>         return True
> 
>+    all_unexpected_passed = (unexpected_total and
>+                             unexpected_total == unexpected_pass_total)
>+    if all_unexpected_passed and not kwargs["fail_on_unexpected_pass"]:
>+        logger.info("Tolerating %i unexpected results because they all PASS" %
>+                    unexpected_pass_total)
>+        return True
>+
>     return unexpected_total == 0
> 
> 
>diff --git a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wpttest.py b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wpttest.py
>index 31b245612be0..0cd72e285b00 100644
>--- a/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wpttest.py
>+++ b/WebDriverTests/imported/w3c/tools/wptrunner/wptrunner/wpttest.py
>@@ -1,9 +1,9 @@
> import os
> import subprocess
> import sys
>-from six.moves.urllib.parse import urljoin
> from collections import defaultdict
>-from six import iteritems, string_types
>+from typing import Any, ClassVar, Dict, Type
>+from urllib.parse import urljoin
> 
> from .wptmanifest.parser import atoms
> 
>@@ -83,7 +83,7 @@ def get_run_info(metadata_root, product, **kwargs):
>     return RunInfo(metadata_root, product, **kwargs)
> 
> 
>-class RunInfo(dict):
>+class RunInfo(Dict[str, Any]):
>     def __init__(self, metadata_root, product, debug,
>                  browser_version=None,
>                  browser_channel=None,
>@@ -150,22 +150,28 @@ def server_protocol(manifest_item):
> 
> class Test(object):
> 
>-    result_cls = None
>-    subtest_result_cls = None
>-    test_type = None
>+    result_cls = None  # type: ClassVar[Type[Result]]
>+    subtest_result_cls = None  # type: ClassVar[Type[SubtestResult]]
>+    test_type = None  # type: ClassVar[str]
> 
>     default_timeout = 10  # seconds
>     long_timeout = 60  # seconds
> 
>-    def __init__(self, tests_root, url, inherit_metadata, test_metadata,
>-                 timeout=None, path=None, protocol="http", quic=False):
>+    def __init__(self, url_base, tests_root, url, inherit_metadata, test_metadata,
>+                 timeout=None, path=None, protocol="http", subdomain=False,
>+                 quic=False):
>+        self.url_base = url_base
>         self.tests_root = tests_root
>         self.url = url
>         self._inherit_metadata = inherit_metadata
>         self._test_metadata = test_metadata
>         self.timeout = timeout if timeout is not None else self.default_timeout
>         self.path = path
>-        self.environment = {"protocol": protocol, "prefs": self.prefs, "quic": quic}
>+        self.subdomain = subdomain
>+        self.environment = {"url_base": url_base,
>+                            "protocol": protocol,
>+                            "prefs": self.prefs,
>+                            "quic": quic}
> 
>     def __eq__(self, other):
>         if not isinstance(other, Test):
>@@ -184,13 +190,15 @@ class Test(object):
>     @classmethod
>     def from_manifest(cls, manifest_file, manifest_item, inherit_metadata, test_metadata):
>         timeout = cls.long_timeout if manifest_item.timeout == "long" else cls.default_timeout
>-        return cls(manifest_file.tests_root,
>+        return cls(manifest_file.url_base,
>+                   manifest_file.tests_root,
>                    manifest_item.url,
>                    inherit_metadata,
>                    test_metadata,
>                    timeout=timeout,
>                    path=os.path.join(manifest_file.tests_root, manifest_item.path),
>-                   protocol=server_protocol(manifest_item))
>+                   protocol=server_protocol(manifest_item),
>+                   subdomain=manifest_item.subdomain)
> 
>     @property
>     def id(self):
>@@ -299,7 +307,7 @@ class Test(object):
>         rv = {}
>         for meta in self.itermeta(None):
>             threshold = meta.leak_threshold
>-            for key, value in iteritems(threshold):
>+            for key, value in threshold.items():
>                 if key not in rv:
>                     rv[key] = value
>         return rv
>@@ -341,7 +349,7 @@ class Test(object):
> 
>         try:
>             expected = metadata.get("expected")
>-            if isinstance(expected, string_types):
>+            if isinstance(expected, str):
>                 return expected
>             elif isinstance(expected, list):
>                 return expected[0]
>@@ -393,11 +401,11 @@ class TestharnessTest(Test):
>     subtest_result_cls = TestharnessSubtestResult
>     test_type = "testharness"
> 
>-    def __init__(self, tests_root, url, inherit_metadata, test_metadata,
>+    def __init__(self, url_base, tests_root, url, inherit_metadata, test_metadata,
>                  timeout=None, path=None, protocol="http", testdriver=False,
>-                 jsshell=False, scripts=None, quic=False):
>-        Test.__init__(self, tests_root, url, inherit_metadata, test_metadata, timeout,
>-                      path, protocol, quic)
>+                 jsshell=False, scripts=None, subdomain=False, quic=False):
>+        Test.__init__(self, url_base, tests_root, url, inherit_metadata, test_metadata, timeout,
>+                      path, protocol, subdomain, quic)
> 
>         self.testdriver = testdriver
>         self.jsshell = jsshell
>@@ -412,7 +420,8 @@ class TestharnessTest(Test):
>         script_metadata = manifest_item.script_metadata or []
>         scripts = [v for (k, v) in script_metadata
>                    if k == "script"]
>-        return cls(manifest_file.tests_root,
>+        return cls(manifest_file.url_base,
>+                   manifest_file.tests_root,
>                    manifest_item.url,
>                    inherit_metadata,
>                    test_metadata,
>@@ -422,6 +431,7 @@ class TestharnessTest(Test):
>                    testdriver=testdriver,
>                    jsshell=jsshell,
>                    scripts=scripts,
>+                   subdomain=manifest_item.subdomain,
>                    quic=quic)
> 
>     @property
>@@ -452,11 +462,11 @@ class ReftestTest(Test):
>     result_cls = ReftestResult
>     test_type = "reftest"
> 
>-    def __init__(self, tests_root, url, inherit_metadata, test_metadata, references,
>-                 timeout=None, path=None, viewport_size=None, dpi=None, fuzzy=None, protocol="http",
>-                 quic=False):
>-        Test.__init__(self, tests_root, url, inherit_metadata, test_metadata, timeout,
>-                      path, protocol, quic)
>+    def __init__(self, url_base, tests_root, url, inherit_metadata, test_metadata, references,
>+                 timeout=None, path=None, viewport_size=None, dpi=None, fuzzy=None,
>+                 protocol="http", subdomain=False, quic=False):
>+        Test.__init__(self, url_base, tests_root, url, inherit_metadata, test_metadata, timeout,
>+                      path, protocol, subdomain, quic)
> 
>         for _, ref_type in references:
>             if ref_type not in ("==", "!="):
>@@ -486,13 +496,15 @@ class ReftestTest(Test):
> 
>         url = manifest_test.url
> 
>-        node = cls(manifest_file.tests_root,
>+        node = cls(manifest_file.url_base,
>+                   manifest_file.tests_root,
>                    manifest_test.url,
>                    inherit_metadata,
>                    test_metadata,
>                    [],
>                    timeout=timeout,
>                    path=manifest_test.path,
>+                   subdomain=manifest_test.subdomain,
>                    quic=quic,
>                    **cls.cls_kwargs(manifest_test))
> 
>@@ -507,20 +519,23 @@ class ReftestTest(Test):
>         # Per the logic documented above, this means that none of the mismatches provided match,
>         mismatch_walk = None
>         if refs_by_type["!="]:
>-            mismatch_walk = ReftestTest(manifest_file.tests_root,
>+            mismatch_walk = ReftestTest(manifest_file.url_base,
>+                                        manifest_file.tests_root,
>                                         refs_by_type["!="][0],
>                                         [],
>                                         None,
>                                         [])
>             cmp_ref = mismatch_walk
>             for ref_url in refs_by_type["!="][1:]:
>-                cmp_self = ReftestTest(manifest_file.tests_root,
>+                cmp_self = ReftestTest(manifest_file.url_base,
>+                                       manifest_file.tests_root,
>                                        url,
>                                        [],
>                                        None,
>                                        [])
>                 cmp_ref.references.append((cmp_self, "!="))
>-                cmp_ref = ReftestTest(manifest_file.tests_root,
>+                cmp_ref = ReftestTest(manifest_file.url_base,
>+                                      manifest_file.tests_root,
>                                       ref_url,
>                                       [],
>                                       None,
>@@ -536,7 +551,8 @@ class ReftestTest(Test):
>             # For each == ref, add a reference to this node whose tail is the mismatch list.
>             # Per the logic documented above, this means any one of the matches must pass plus all the mismatches.
>             for ref_url in refs_by_type["=="]:
>-                ref = ReftestTest(manifest_file.tests_root,
>+                ref = ReftestTest(manifest_file.url_base,
>+                                  manifest_file.tests_root,
>                                   ref_url,
>                                   [],
>                                   None,
>@@ -605,12 +621,12 @@ class ReftestTest(Test):
> class PrintReftestTest(ReftestTest):
>     test_type = "print-reftest"
> 
>-    def __init__(self, tests_root, url, inherit_metadata, test_metadata, references,
>+    def __init__(self, url_base, tests_root, url, inherit_metadata, test_metadata, references,
>                  timeout=None, path=None, viewport_size=None, dpi=None, fuzzy=None,
>-                 page_ranges=None, protocol="http", quic=False):
>-        super(PrintReftestTest, self).__init__(tests_root, url, inherit_metadata, test_metadata,
>+                 page_ranges=None, protocol="http", subdomain=False, quic=False):
>+        super(PrintReftestTest, self).__init__(url_base, tests_root, url, inherit_metadata, test_metadata,
>                                                references, timeout, path, viewport_size, dpi,
>-                                               fuzzy, protocol, quic=quic)
>+                                               fuzzy, protocol, subdomain=subdomain, quic=quic)
>         self._page_ranges = page_ranges
> 
>     @classmethod
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/accept_alert/accept.py b/WebDriverTests/imported/w3c/webdriver/tests/accept_alert/accept.py
>index 711ad5af79f2..b83477e5ca72 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/accept_alert/accept.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/accept_alert/accept.py
>@@ -1,7 +1,9 @@
>+import pytest
>+
> from webdriver.error import NoSuchAlertException
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
>+from tests.support.helpers import wait_for_new_handle
> from tests.support.sync import Poll
> 
> 
>@@ -10,7 +12,7 @@ def accept_alert(session):
>         "POST", "session/{session_id}/alert/accept".format(**vars(session)))
> 
> 
>-def test_null_response_value(session, url):
>+def test_null_response_value(session, inline):
>     session.url = inline("<script>window.alert('Hello');</script>")
> 
>     response = accept_alert(session)
>@@ -33,27 +35,41 @@ def test_no_user_prompt(session):
>     assert_error(response, "no such alert")
> 
> 
>-def test_accept_alert(session):
>+def test_accept_alert(session, inline):
>     session.url = inline("<script>window.alert('Hello');</script>")
>+
>     response = accept_alert(session)
>     assert_success(response)
> 
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>+
> 
>-def test_accept_confirm(session):
>+def test_accept_confirm(session, inline):
>     session.url = inline("<script>window.result = window.confirm('Hello');</script>")
>+
>     response = accept_alert(session)
>     assert_success(response)
>+
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>+
>     assert session.execute_script("return window.result") is True
> 
> 
>-def test_accept_prompt(session):
>+def test_accept_prompt(session, inline):
>     session.url = inline("""
>         <script>
>           window.result = window.prompt('Enter Your Name: ', 'Federer');
>         </script>
>         """)
>+
>     response = accept_alert(session)
>     assert_success(response)
>+
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>+
>     assert session.execute_script("return window.result") == "Federer"
> 
> 
>@@ -68,3 +84,27 @@ def test_unexpected_alert(session):
> 
>     response = accept_alert(session)
>     assert_success(response)
>+
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>+
>+
>+def test_accept_in_popup_window(session, inline):
>+    orig_handles = session.handles
>+
>+    session.url = inline("""
>+        <button onclick="window.open('about:blank', '_blank', 'width=500; height=200;resizable=yes');">open</button>
>+        """)
>+    button = session.find.css("button", all=False)
>+    button.click()
>+
>+    session.window_handle = wait_for_new_handle(session, orig_handles)
>+    session.url = inline("""
>+        <script>window.alert("Hello")</script>
>+        """)
>+
>+    response = accept_alert(session)
>+    assert_success(response)
>+
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/add_cookie/add.py b/WebDriverTests/imported/w3c/webdriver/tests/add_cookie/add.py
>index f05153790261..3a19432fc6a2 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/add_cookie/add.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/add_cookie/add.py
>@@ -1,13 +1,13 @@
> import pytest
> 
> from datetime import datetime, timedelta
>-from six import text_type
> 
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_success
> from tests.support.helpers import clear_all_cookies
> 
>+
> def add_cookie(session, cookie):
>     return session.transport.send(
>         "POST", "session/{session_id}/cookie".format(**vars(session)),
>@@ -54,6 +54,43 @@ def test_no_browsing_context(session, closed_frame):
>     assert_error(response, "no such window")
> 
> 
>+@pytest.mark.parametrize(
>+    "page",
>+    [
>+        "about:blank",
>+        "blob:foo/bar",
>+        "data:text/html;charset=utf-8,<p>foo</p>",
>+        "file:///foo/bar",
>+        "ftp://example.org",
>+        "javascript:foo",
>+        "ws://example.org",
>+        "wss://example.org",
>+    ],
>+    ids=[
>+        "about",
>+        "blob",
>+        "data",
>+        "file",
>+        "ftp",
>+        "javascript",
>+        "websocket",
>+        "secure websocket",
>+    ],
>+)
>+def test_cookie_unsupported_scheme(session, page):
>+    new_cookie = {
>+        "name": "hello",
>+        "value": "world",
>+        "domain": page,
>+        "path": "/",
>+        "httpOnly": False,
>+        "secure": False
>+    }
>+
>+    result = add_cookie(session, new_cookie)
>+    assert_error(result, "invalid cookie domain")
>+
>+
> def test_add_domain_cookie(session, url, server_config):
>     new_cookie = {
>         "name": "hello",
>@@ -72,11 +109,11 @@ def test_add_domain_cookie(session, url, server_config):
> 
>     cookie = session.cookies("hello")
>     assert "domain" in cookie
>-    assert isinstance(cookie["domain"], text_type)
>+    assert isinstance(cookie["domain"], str)
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
> 
>     assert cookie["name"] == "hello"
>     assert cookie["value"] == "world"
>@@ -102,11 +139,11 @@ def test_add_cookie_for_ip(session, url, server_config, configuration):
> 
>     cookie = session.cookies("hello")
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
>     assert "domain" in cookie
>-    assert isinstance(cookie["domain"], text_type)
>+    assert isinstance(cookie["domain"], str)
> 
>     assert cookie["name"] == "hello"
>     assert cookie["value"] == "world"
>@@ -131,9 +168,9 @@ def test_add_non_session_cookie(session, url):
> 
>     cookie = session.cookies("hello")
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
>     assert "expiry" in cookie
>     assert isinstance(cookie["expiry"], int)
> 
>@@ -156,9 +193,9 @@ def test_add_session_cookie(session, url):
> 
>     cookie = session.cookies("hello")
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
>     if "expiry" in cookie:
>         assert cookie.get("expiry") is None
> 
>@@ -181,11 +218,11 @@ def test_add_session_cookie_with_leading_dot_character_in_domain(session, url, s
> 
>     cookie = session.cookies("hello")
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
>     assert "domain" in cookie
>-    assert isinstance(cookie["domain"], text_type)
>+    assert isinstance(cookie["domain"], str)
> 
>     assert cookie["name"] == "hello"
>     assert cookie["value"] == "world"
>@@ -209,11 +246,11 @@ def test_add_cookie_with_valid_samesite_flag(session, url, same_site):
> 
>     cookie = session.cookies("hello")
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
>     assert "sameSite" in cookie
>-    assert isinstance(cookie["sameSite"], text_type)
>+    assert isinstance(cookie["sameSite"], str)
> 
>     assert cookie["name"] == "hello"
>     assert cookie["value"] == "world"
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/back/back.py b/WebDriverTests/imported/w3c/webdriver/tests/back/back.py
>index 9ca52e8f223e..86ad2278ab39 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/back/back.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/back/back.py
>@@ -1,4 +1,6 @@
>-from tests.support.inline import inline
>+import pytest
>+from webdriver import error
>+
> from tests.support.asserts import assert_error, assert_success
> 
> 
>@@ -7,7 +9,7 @@ def back(session):
>         "POST", "session/{session_id}/back".format(**vars(session)))
> 
> 
>-def test_null_response_value(session):
>+def test_null_response_value(session, inline):
>     session.url = inline("<div>")
>     session.url = inline("<p>")
> 
>@@ -31,7 +33,7 @@ def test_no_browsing_history(session):
>     assert_success(response)
> 
> 
>-def test_data_urls(session):
>+def test_data_urls(session, inline):
>     test_pages = [
>         inline("<p id=1>"),
>         inline("<p id=2>"),
>@@ -46,7 +48,7 @@ def test_data_urls(session):
>     assert session.url == test_pages[0]
> 
> 
>-def test_dismissed_beforeunload(session):
>+def test_dismissed_beforeunload(session, inline):
>     url_beforeunload = inline("""
>       <input type="text">
>       <script>
>@@ -88,7 +90,7 @@ def test_fragments(session, url):
>     assert session.url == test_pages[0]
> 
> 
>-def test_history_pushstate(session, url):
>+def test_history_pushstate(session, inline):
>     pushstate_page = inline("""
>       <script>
>         function pushState() {
>@@ -109,3 +111,42 @@ def test_history_pushstate(session, url):
> 
>     assert session.url == pushstate_page
>     assert session.execute_script("return history.state;") is None
>+
>+
>+def test_removed_iframe(session, url, inline):
>+    page = inline("<p>foo")
>+
>+    session.url = page
>+    session.url = url("/webdriver/tests/support/html/frames_no_bfcache.html")
>+
>+    subframe = session.find.css("#sub-frame", all=False)
>+    session.switch_frame(subframe)
>+
>+    response = back(session)
>+    assert_success(response)
>+
>+    assert session.url == page
>+
>+
>+# Capability needed as long as no valid certificate is available:
>+#   https://github.com/web-platform-tests/wpt/issues/28847
>+@pytest.mark.capabilities({"acceptInsecureCerts": True})
>+def test_cross_origin(session, url):
>+    base_path = ("/webdriver/tests/support/html/subframe.html" +
>+                 "?pipe=header(Cross-Origin-Opener-Policy,same-origin")
>+    first_page = url(base_path, protocol="https")
>+    second_page = url(base_path, protocol="https", domain="alt")
>+
>+    session.url = first_page
>+    session.url = second_page
>+
>+    elem = session.find.css("#delete", all=False)
>+
>+    response = back(session)
>+    assert_success(response)
>+
>+    assert session.url == first_page
>+
>+    with pytest.raises(error.StaleElementReferenceException):
>+        elem.click()
>+    elem = session.find.css("#delete", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/back/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/back/user_prompts.py
>index 7121f7c6b2a6..9d04f0f4ab12 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/back/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/back/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def back(session):
>@@ -12,7 +11,7 @@ def back(session):
> 
> 
> @pytest.fixture
>-def pages(session):
>+def pages(session, inline):
>     pages = [
>         inline("<p id=1>"),
>         inline("<p id=2>"),
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/bidi/new_session/__init__.py b/WebDriverTests/imported/w3c/webdriver/tests/bidi/new_session/__init__.py
>new file mode 100644
>index 000000000000..e69de29bb2d1
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/bidi/new_session/connect.py b/WebDriverTests/imported/w3c/webdriver/tests/bidi/new_session/connect.py
>new file mode 100644
>index 000000000000..357da31ba862
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/bidi/new_session/connect.py
>@@ -0,0 +1,34 @@
>+import pytest
>+import asyncio
>+import websockets
>+import webdriver
>+
>+# classic session to enable bidi capability manually
>+# Intended to be the first test in this file
>+@pytest.mark.asyncio
>+@pytest.mark.capabilities({"webSocketUrl": True})
>+async def test_websocket_url_connect(session):
>+    websocket_url = session.capabilities["webSocketUrl"]
>+    async with websockets.connect(websocket_url) as websocket:
>+        await websocket.send("Hello world!")
>+
>+# test bidi_session send
>+# using bidi_session is the recommended way to test bidi
>+@pytest.mark.asyncio
>+async def test_bidi_session_send(bidi_session):
>+    await bidi_session.send_command("test.test", {})
>+
>+# bidi session following a bidi session with a different capabilities
>+# to test session recreation
>+@pytest.mark.asyncio
>+@pytest.mark.capabilities({"acceptInsecureCerts": True})
>+async def test_bidi_session_with_different_capability(bidi_session):
>+    await bidi_session.send_command("test.test", {})
>+
>+# classic session following a bidi session to test session
>+# recreation
>+# Intended to be the last test in this file to make sure
>+# classic session is not impacted by bidi tests
>+@pytest.mark.asyncio
>+def test_classic_after_bidi_session(session):
>+    assert not isinstance(session, webdriver.bidi.BidiSession)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/close_window/close.py b/WebDriverTests/imported/w3c/webdriver/tests/close_window/close.py
>index 53af5730f83f..7b382fa9bbcb 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/close_window/close.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/close_window/close.py
>@@ -2,7 +2,6 @@ import pytest
> from webdriver import error
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def close(session):
>@@ -46,7 +45,7 @@ def test_close_browsing_context(session):
>     assert new_handle not in handles
> 
> 
>-def test_close_browsing_context_with_dismissed_beforeunload_prompt(session):
>+def test_close_browsing_context_with_dismissed_beforeunload_prompt(session, inline):
>     original_handles = session.handles
> 
>     new_handle = session.new_window()
>@@ -81,3 +80,23 @@ def test_close_last_browsing_context(session):
> 
>     # With no more open top-level browsing contexts, the session is closed.
>     session.session_id = None
>+
>+
>+def test_element_usage_after_closing_browsing_context(session, inline):
>+    session.url = inline("<p id='a'>foo")
>+    a = session.find.css("p", all=False)
>+    first = session.window_handle
>+
>+    second = session.new_window(type_hint="tab")
>+    session.window_handle = second
>+
>+    session.url = inline("<p id='b'>other")
>+    b = session.find.css("p", all=False)
>+
>+    session.window_handle = first
>+    response = close(session)
>+    assert_success(response)
>+    assert len(session.handles) == 1
>+
>+    session.window_handle = second
>+    assert b.attribute("id") == "b"
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/delete_session/delete.py b/WebDriverTests/imported/w3c/webdriver/tests/delete_session/delete.py
>index d0b4d796308e..a3032cc13475 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/delete_session/delete.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/delete_session/delete.py
>@@ -2,7 +2,6 @@ import pytest
> from webdriver import error
> 
> from tests.support.asserts import assert_success
>-from tests.support.inline import inline
> 
> 
> def delete_session(session):
>@@ -19,7 +18,7 @@ def test_null_response_value(session):
>     session.end()
> 
> 
>-def test_dismissed_beforeunload_prompt(session):
>+def test_dismissed_beforeunload_prompt(session, inline):
>     session.url = inline("""
>       <input type="text">
>       <script>
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/dismiss_alert/dismiss.py b/WebDriverTests/imported/w3c/webdriver/tests/dismiss_alert/dismiss.py
>index da65bac388df..a28dec768750 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/dismiss_alert/dismiss.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/dismiss_alert/dismiss.py
>@@ -1,7 +1,9 @@
>+import pytest
>+
> from webdriver.error import NoSuchAlertException
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
>+from tests.support.helpers import wait_for_new_handle
> from tests.support.sync import Poll
> 
> 
>@@ -10,7 +12,7 @@ def dismiss_alert(session):
>         "POST", "session/{session_id}/alert/dismiss".format(**vars(session)))
> 
> 
>-def test_null_response_value(session, url):
>+def test_null_response_value(session, inline):
>     session.url = inline("<script>window.alert('Hello');</script>")
> 
>     response = dismiss_alert(session)
>@@ -33,28 +35,45 @@ def test_no_user_prompt(session):
>     assert_error(response, "no such alert")
> 
> 
>-def test_dismiss_alert(session):
>+def test_dismiss_alert(session, inline):
>     session.url = inline("<script>window.alert('Hello');</script>")
>+
>     response = dismiss_alert(session)
>     assert_success(response)
> 
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>+
> 
>-def test_dismiss_confirm(session):
>+def test_dismiss_confirm(session, inline):
>     session.url = inline("<script>window.result = window.confirm('Hello');</script>")
>+
>     response = dismiss_alert(session)
>     assert_success(response)
>+
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>+
>     assert session.execute_script("return window.result;") is False
> 
> 
>-def test_dismiss_prompt(session):
>-    session.url = inline("<script>window.result = window.prompt('Enter Your Name: ', 'Federer');</script>")
>+def test_dismiss_prompt(session, inline):
>+    session.url = inline("""
>+        <script>window.result = window.prompt('Enter Your Name: ', 'Federer');</script>
>+        """)
>+
>     response = dismiss_alert(session)
>     assert_success(response)
>+
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>+
>     assert session.execute_script("return window.result") is None
> 
> 
> def test_unexpected_alert(session):
>     session.execute_script("setTimeout(function() { alert('Hello'); }, 100);")
>+
>     wait = Poll(
>         session,
>         timeout=5,
>@@ -64,3 +83,27 @@ def test_unexpected_alert(session):
> 
>     response = dismiss_alert(session)
>     assert_success(response)
>+
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>+
>+
>+def test_dismiss_in_popup_window(session, inline):
>+    orig_handles = session.handles
>+
>+    session.url = inline("""
>+        <button onclick="window.open('about:blank', '_blank', 'width=500; height=200;resizable=yes');">open</button>
>+        """)
>+    button = session.find.css("button", all=False)
>+    button.click()
>+
>+    session.window_handle = wait_for_new_handle(session, orig_handles)
>+    session.url = inline("""
>+        <script>window.alert("Hello")</script>
>+        """)
>+
>+    response = dismiss_alert(session)
>+    assert_success(response)
>+
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_clear/clear.py b/WebDriverTests/imported/w3c/webdriver/tests/element_clear/clear.py
>index 0189c38c2770..b65f443aa758 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_clear/clear.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_clear/clear.py
>@@ -11,7 +11,6 @@ from tests.support.asserts import (
>     assert_in_events,
>     assert_success,
> )
>-from tests.support.inline import inline
> 
> 
> @pytest.fixture
>@@ -37,7 +36,7 @@ def text_file(tmpdir_factory):
>     return fh
> 
> 
>-def test_null_response_value(session):
>+def test_null_response_value(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>@@ -48,10 +47,17 @@ def test_null_response_value(session):
> 
> def test_no_top_browsing_context(session, closed_window):
>     element = Element("foo", session)
>+    response = element_clear(session, element)
>+    assert_error(response, "no such window")
> 
>+    original_handle, element = closed_window
>     response = element_clear(session, element)
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = element_clear(session, element)
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     element = Element("foo", session)
>@@ -60,7 +66,7 @@ def test_no_browsing_context(session, closed_frame):
>     assert_error(response, "no such window")
> 
> 
>-def test_connected_element(session):
>+def test_connected_element(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>@@ -69,7 +75,7 @@ def test_connected_element(session):
>     assert_error(response, "stale element reference")
> 
> 
>-def test_pointer_interactable(session):
>+def test_pointer_interactable(session, inline):
>     session.url = inline("<input style='margin-left: -1000px' value=foobar>")
>     element = session.find.css("input", all=False)
> 
>@@ -77,7 +83,7 @@ def test_pointer_interactable(session):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_keyboard_interactable(session):
>+def test_keyboard_interactable(session, inline):
>     session.url = inline("""
>         <input value=foobar>
>         <div></div>
>@@ -114,7 +120,7 @@ def test_keyboard_interactable(session):
>                           ("time", "19:48", ""),
>                           ("month", "2017-11", ""),
>                           ("week", "2017-W52", "")])
>-def test_input(session, add_event_listeners, tracked_events, type, value, default):
>+def test_input(session, inline, add_event_listeners, tracked_events, type, value, default):
>     session.url = inline("<input type=%s value='%s'>" % (type, value))
>     element = session.find.css("input", all=False)
>     add_event_listeners(element, tracked_events)
>@@ -144,7 +150,7 @@ def test_input(session, add_event_listeners, tracked_events, type, value, defaul
>                           "month",
>                           "week",
>                           "file"])
>-def test_input_disabled(session, type):
>+def test_input_disabled(session, inline, type):
>     session.url = inline("<input type=%s disabled>" % type)
>     element = session.find.css("input", all=False)
> 
>@@ -169,7 +175,7 @@ def test_input_disabled(session, type):
>                           "month",
>                           "week",
>                           "file"])
>-def test_input_readonly(session, type):
>+def test_input_readonly(session, inline, type):
>     session.url = inline("<input type=%s readonly>" % type)
>     element = session.find.css("input", all=False)
> 
>@@ -177,7 +183,7 @@ def test_input_readonly(session, type):
>     assert_error(response, "invalid element state")
> 
> 
>-def test_textarea(session, add_event_listeners, tracked_events):
>+def test_textarea(session, inline, add_event_listeners, tracked_events):
>     session.url = inline("<textarea>foobar</textarea>")
>     element = session.find.css("textarea", all=False)
>     add_event_listeners(element, tracked_events)
>@@ -189,7 +195,7 @@ def test_textarea(session, add_event_listeners, tracked_events):
>     assert_in_events(session, ["focus", "change", "blur"])
> 
> 
>-def test_textarea_disabled(session):
>+def test_textarea_disabled(session, inline):
>     session.url = inline("<textarea disabled></textarea>")
>     element = session.find.css("textarea", all=False)
> 
>@@ -197,7 +203,7 @@ def test_textarea_disabled(session):
>     assert_error(response, "invalid element state")
> 
> 
>-def test_textarea_readonly(session):
>+def test_textarea_readonly(session, inline):
>     session.url = inline("<textarea readonly></textarea>")
>     element = session.find.css("textarea", all=False)
> 
>@@ -205,7 +211,7 @@ def test_textarea_readonly(session):
>     assert_error(response, "invalid element state")
> 
> 
>-def test_input_file(session, text_file):
>+def test_input_file(session, text_file, inline):
>     session.url = inline("<input type=file>")
>     element = session.find.css("input", all=False)
>     element.send_keys(str(text_file))
>@@ -215,7 +221,7 @@ def test_input_file(session, text_file):
>     assert element.property("value") == ""
> 
> 
>-def test_input_file_multiple(session, text_file):
>+def test_input_file_multiple(session, text_file, inline):
>     session.url = inline("<input type=file multiple>")
>     element = session.find.css("input", all=False)
>     element.send_keys(str(text_file))
>@@ -226,7 +232,7 @@ def test_input_file_multiple(session, text_file):
>     assert element.property("value") == ""
> 
> 
>-def test_select(session):
>+def test_select(session, inline):
>     session.url = inline("""
>         <select>
>           <option>foo
>@@ -241,7 +247,7 @@ def test_select(session):
>     assert_error(response, "invalid element state")
> 
> 
>-def test_button(session):
>+def test_button(session, inline):
>     session.url = inline("<button></button>")
>     button = session.find.css("button", all=False)
> 
>@@ -249,7 +255,7 @@ def test_button(session):
>     assert_error(response, "invalid element state")
> 
> 
>-def test_button_with_subtree(session):
>+def test_button_with_subtree(session, inline):
>     """
>     Elements inside button elements are interactable.
>     """
>@@ -264,7 +270,7 @@ def test_button_with_subtree(session):
>     assert_success(response)
> 
> 
>-def test_contenteditable(session, add_event_listeners, tracked_events):
>+def test_contenteditable(session, inline, add_event_listeners, tracked_events):
>     session.url = inline("<p contenteditable>foobar</p>")
>     element = session.find.css("p", all=False)
>     add_event_listeners(element, tracked_events)
>@@ -277,7 +283,7 @@ def test_contenteditable(session, add_event_listeners, tracked_events):
>     assert_element_has_focus(session.execute_script("return document.body"))
> 
> 
>-def test_designmode(session):
>+def test_designmode(session, inline):
>     session.url = inline("foobar")
>     element = session.find.css("body", all=False)
>     assert element.property("innerHTML") == "foobar"
>@@ -289,7 +295,7 @@ def test_designmode(session):
>     assert_element_has_focus(session.execute_script("return document.body"))
> 
> 
>-def test_resettable_element_focus_when_empty(session, add_event_listeners, tracked_events):
>+def test_resettable_element_focus_when_empty(session, inline, add_event_listeners, tracked_events):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
>     add_event_listeners(element, tracked_events)
>@@ -313,7 +319,7 @@ def test_resettable_element_focus_when_empty(session, add_event_listeners, track
>                           ("time", "foo"),
>                           ("month", "foo"),
>                           ("week", "foo")])
>-def test_resettable_element_does_not_satisfy_validation_constraints(session, type, invalid_value):
>+def test_resettable_element_does_not_satisfy_validation_constraints(session, inline, type, invalid_value):
>     """
>     Some UAs allow invalid input to certain types of constrained
>     form controls.  For example, Gecko allows non-valid characters
>@@ -350,7 +356,7 @@ def test_resettable_element_does_not_satisfy_validation_constraints(session, typ
>                           "submit",
>                           "button",
>                           "image"])
>-def test_non_editable_inputs(session, type):
>+def test_non_editable_inputs(session, inline, type):
>     session.url = inline("<input type=%s>" % type)
>     element = session.find.css("input", all=False)
> 
>@@ -358,7 +364,7 @@ def test_non_editable_inputs(session, type):
>     assert_error(response, "invalid element state")
> 
> 
>-def test_scroll_into_view(session):
>+def test_scroll_into_view(session, inline):
>     session.url = inline("""
>         <input value=foobar>
>         <div style='height: 200vh; width: 5000vh'>
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_clear/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/element_clear/user_prompts.py
>index cfb850e08d5a..7a8564a684a7 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_clear/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_clear/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def element_clear(session, element):
>@@ -14,7 +13,7 @@ def element_clear(session, element):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input type=text>")
>         element = session.find.css("input", all=False)
>@@ -35,7 +34,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input type=text>")
>         element = session.find.css("input", all=False)
>@@ -56,7 +55,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input type=text>")
>         element = session.find.css("input", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/bubbling.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/bubbling.py
>index a069a5a5df3d..7620ec3224fc 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/bubbling.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/bubbling.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_success
>-from tests.support.inline import inline
> 
> 
> def element_click(session, element):
>@@ -9,7 +8,7 @@ def element_click(session, element):
>             element_id=element.id))
> 
> 
>-def test_click_event_bubbles_to_parents(session):
>+def test_click_event_bubbles_to_parents(session, inline):
>     session.url = inline("""
>         <style>
>         body * {
>@@ -45,7 +44,7 @@ def test_click_event_bubbles_to_parents(session):
>     assert three in clicks
> 
> 
>-def test_spin_event_loop(session):
>+def test_spin_event_loop(session, inline):
>     """
>     Wait until the user agent event loop has spun enough times to
>     process the DOM events generated by clicking.
>@@ -86,7 +85,7 @@ def test_spin_event_loop(session):
>     assert three in delayed_clicks
> 
> 
>-def test_element_disappears_during_click(session):
>+def test_element_disappears_during_click(session, inline):
>     """
>     When an element in the event bubbling order disappears (its CSS
>     display style is set to "none") during a click, Gecko and Blink
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/center_point.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/center_point.py
>index da60a087277d..ef0c9a7fe27d 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/center_point.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/center_point.py
>@@ -2,7 +2,6 @@ import pytest
> 
> from tests.support.asserts import assert_error, assert_success
> from tests.support.helpers import center_point
>-from tests.support.inline import inline
> 
> 
> def element_click(session, element):
>@@ -12,7 +11,7 @@ def element_click(session, element):
>             element_id=element.id))
> 
> 
>-def square(size):
>+def square(inline, size):
>     return inline("""
>         <style>
>         body {{ margin: 0 }}
>@@ -41,8 +40,8 @@ def assert_one_click(session):
>     return tuple(clicks[0])
> 
> 
>-def test_entirely_in_view(session):
>-    session.url = square(444)
>+def test_entirely_in_view(session, inline):
>+    session.url = square(inline, 444)
>     element = session.find.css("#target", all=False)
> 
>     response = element_click(session, element)
>@@ -53,8 +52,8 @@ def test_entirely_in_view(session):
> 
> 
> @pytest.mark.parametrize("size", range(1, 11))
>-def test_css_pixel_rounding(session, size):
>-    session.url = square(size)
>+def test_css_pixel_rounding(session, inline, size):
>+    session.url = square(inline, size)
>     element = session.find.css("#target", all=False)
>     expected_click_point = center_point(element)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/click.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/click.py
>index 3a5d737216d9..b1b10162e4d6 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/click.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/click.py
>@@ -1,7 +1,6 @@
> from webdriver import Element
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def element_click(session, element):
>@@ -11,7 +10,7 @@ def element_click(session, element):
>             element_id=element.id))
> 
> 
>-def test_null_response_value(session):
>+def test_null_response_value(session, inline):
>     session.url = inline("<p>foo")
>     element = session.find.css("p", all=False)
> 
>@@ -22,10 +21,17 @@ def test_null_response_value(session):
> 
> def test_no_top_browsing_context(session, closed_window):
>     element = Element("foo", session)
>+    response = element_click(session, element)
>+    assert_error(response, "no such window")
> 
>+    original_handle, element = closed_window
>     response = element_click(session, element)
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = element_click(session, element)
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     element = Element("foo", session)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/events.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/events.py
>new file mode 100644
>index 000000000000..e3d32c1bcb44
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/events.py
>@@ -0,0 +1,33 @@
>+from webdriver import Element
>+from tests.support.asserts import assert_success
>+from tests.support.helpers import filter_dict
>+
>+def get_events(session):
>+    """Return list of mouse events recorded in the fixture."""
>+    return session.execute_script("return allEvents.events;") or []
>+
>+def element_click(session, element):
>+    return session.transport.send(
>+        "POST", "session/{session_id}/element/{element_id}/click".format(
>+            session_id=session.session_id,
>+            element_id=element.id))
>+
>+def test_event_mousemove(session, url):
>+    session.url = url("/webdriver/tests/element_click/support/test_click_wdspec.html")
>+
>+    element = session.find.css('#outer', all=False)
>+    response = element_click(session, element)
>+    assert_success(response)
>+
>+    events = get_events(session)
>+    assert len(events) == 4
>+
>+    expected = [
>+        {"type": "mousemove", "buttons": 0, "button": 0},
>+        {"type": "mousedown", "buttons": 1, "button": 0},
>+        {"type": "mouseup", "buttons": 0, "button": 0},
>+        {"type": "click", "buttons": 0, "button": 0},
>+    ]
>+    filtered_events = [filter_dict(e, expected[0]) for e in events]
>+
>+    assert expected == filtered_events
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/file_upload.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/file_upload.py
>index cd5bb434204d..73832d0f85ae 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/file_upload.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/file_upload.py
>@@ -1,5 +1,5 @@
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
>+
> 
> def element_click(session, element):
>     return session.transport.send(
>@@ -8,7 +8,7 @@ def element_click(session, element):
>             element_id=element.id))
> 
> 
>-def test_file_upload_state(session):
>+def test_file_upload_state(session,inline):
>     session.url = inline("<input type=file>")
> 
>     element = session.find.css("input", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/interactability.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/interactability.py
>index 7463d493e3d8..d55860c8746f 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/interactability.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/interactability.py
>@@ -1,7 +1,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def element_click(session, element):
>@@ -11,7 +10,7 @@ def element_click(session, element):
>             element_id=element.id))
> 
> 
>-def test_display_none(session):
>+def test_display_none(session, inline):
>     session.url = inline("""<button style="display: none">foobar</button>""")
>     element = session.find.css("button", all=False)
> 
>@@ -19,7 +18,7 @@ def test_display_none(session):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_visibility_hidden(session):
>+def test_visibility_hidden(session, inline):
>     session.url = inline("""<button style="visibility: hidden">foobar</button>""")
>     element = session.find.css("button", all=False)
> 
>@@ -27,7 +26,7 @@ def test_visibility_hidden(session):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_hidden(session):
>+def test_hidden(session, inline):
>     session.url = inline("<button hidden>foobar</button>")
>     element = session.find.css("button", all=False)
> 
>@@ -35,7 +34,7 @@ def test_hidden(session):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_disabled(session):
>+def test_disabled(session, inline):
>     session.url = inline("""<button disabled>foobar</button>""")
>     element = session.find.css("button", all=False)
> 
>@@ -44,7 +43,7 @@ def test_disabled(session):
> 
> 
> @pytest.mark.parametrize("transform", ["translate(-100px, -100px)", "rotate(50deg)"])
>-def test_element_not_interactable_css_transform(session, transform):
>+def test_element_not_interactable_css_transform(session, inline, transform):
>     session.url = inline("""
>         <div style="width: 500px; height: 100px;
>             background-color: blue; transform: {transform};">
>@@ -55,7 +54,7 @@ def test_element_not_interactable_css_transform(session, transform):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_element_not_interactable_out_of_view(session):
>+def test_element_not_interactable_out_of_view(session, inline):
>     session.url = inline("""
>         <style>
>         input {
>@@ -73,7 +72,7 @@ def test_element_not_interactable_out_of_view(session):
> 
> 
> @pytest.mark.parametrize("tag_name", ["div", "span"])
>-def test_zero_sized_element(session, tag_name):
>+def test_zero_sized_element(session, inline, tag_name):
>     session.url = inline("<{0}></{0}>".format(tag_name))
>     element = session.find.css(tag_name, all=False)
> 
>@@ -81,7 +80,7 @@ def test_zero_sized_element(session, tag_name):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_element_intercepted(session):
>+def test_element_intercepted(session, inline):
>     session.url = inline("""
>         <style>
>         div {
>@@ -102,14 +101,14 @@ def test_element_intercepted(session):
>     assert_error(response, "element click intercepted")
> 
> 
>-def test_element_intercepted_no_pointer_events(session):
>+def test_element_intercepted_no_pointer_events(session, inline):
>     session.url = inline("""<input type=button value=Roger style="pointer-events: none">""")
>     element = session.find.css("input", all=False)
>     response = element_click(session, element)
>     assert_error(response, "element click intercepted")
> 
> 
>-def test_element_not_visible_overflow_hidden(session):
>+def test_element_not_visible_overflow_hidden(session, inline):
>     session.url = inline("""
>         <style>
>         div {
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/navigate.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/navigate.py
>index d776a1eb84e6..492718292a17 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/navigate.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/navigate.py
>@@ -1,5 +1,9 @@
>+import pytest
>+
>+from webdriver.error import NoSuchElementException
>+
> from tests.support.asserts import assert_success
>-from tests.support.inline import inline
>+from tests.support.helpers import wait_for_new_handle
> from tests.support.sync import Poll
> 
> 
>@@ -10,7 +14,7 @@ def element_click(session, element):
>             element_id=element.id))
> 
> 
>-def test_numbers_link(session, server_config):
>+def test_numbers_link(session, server_config, inline):
>     link = "/webdriver/tests/element_click/support/input.html"
>     session.url = inline("<a href={url}>123456</a>".format(url=link))
>     element = session.find.css("a", all=False)
>@@ -22,7 +26,7 @@ def test_numbers_link(session, server_config):
>     assert session.url == "http://{host}:{port}{url}".format(host=host, port=port, url=link)
> 
> 
>-def test_multi_line_link(session, server_config):
>+def test_multi_line_link(session, server_config, inline):
>     link = "/webdriver/tests/element_click/support/input.html"
>     session.url = inline("""
>         <p style="background-color: yellow; width: 50px;">
>@@ -37,7 +41,7 @@ def test_multi_line_link(session, server_config):
>     assert session.url == "http://{host}:{port}{url}".format(host=host, port=port, url=link)
> 
> 
>-def test_link_unload_event(session, server_config):
>+def test_link_unload_event(session, server_config, inline):
>     link = "/webdriver/tests/element_click/support/input.html"
>     session.url = inline("""
>         <body onunload="checkUnload()">
>@@ -68,7 +72,7 @@ def test_link_unload_event(session, server_config):
>     assert response is True
> 
> 
>-def test_link_hash(session):
>+def test_link_hash(session, inline):
>     id = "anchor"
>     session.url = inline("""
>         <a href="#{url}">aaaa</a>
>@@ -93,34 +97,94 @@ def test_link_hash(session):
>             """, args=(element,)) is True
> 
> 
>-def test_link_open_target_in_new_window(session, url):
>-    orig_handles = session.handles
>+@pytest.mark.parametrize("target", [
>+    "",
>+    "_blank",
>+    "_parent",
>+    "_self",
>+    "_top",
>+])
>+def test_link_from_toplevel_context_with_target(session, inline, target):
>+    target_page = inline("<p id='foo'>foo</p>")
> 
>-    session.url = inline("""
>-        <a href="{}" target="_blank">Open in new window</a>
>-    """.format(inline("<p id=foo")))
>+    session.url = inline("<a href='{}' target='{}'>click</a>".format(target_page, target))
>     element = session.find.css("a", all=False)
> 
>+    orig_handles = session.handles
>+
>     response = element_click(session, element)
>     assert_success(response)
> 
>-    def find_new_handle(session):
>-        new_handles = list(set(session.handles) - set(orig_handles))
>-        if new_handles and len(new_handles) == 1:
>-            return new_handles[0]
>-        return None
>+    if target == "_blank":
>+        session.window_handle = wait_for_new_handle(session, orig_handles)
> 
>     wait = Poll(
>         session,
>         timeout=5,
>-        message="No new window has been opened")
>-    new_handle = wait.until(find_new_handle)
>+        ignored_exceptions=NoSuchElementException,
>+        message="Expected element has not been found")
>+    wait.until(lambda s: s.find.css("#foo"))
>+
>+
>+@pytest.mark.parametrize("target", [
>+    "",
>+    "_blank",
>+    "_parent",
>+    "_self",
>+    "_top",
>+])
>+def test_link_from_nested_context_with_target(session, inline, iframe, target):
>+    target_page = inline("<p id='foo'>foo</p>")
>+
>+    session.url = inline(iframe("<a href='{}' target='{}'>click</a>".format(target_page, target)))
>+    frame = session.find.css("iframe", all=False)
>+    session.switch_frame(frame)
>+    element = session.find.css("a".format(target), all=False)
> 
>-    session.window_handle = new_handle
>-    session.find.css("#foo")
>+    orig_handles = session.handles
>+
>+    response = element_click(session, element)
>+    assert_success(response)
>+
>+    if target == "_blank":
>+        session.window_handle = wait_for_new_handle(session, orig_handles)
>+
>+    # With the current browsing context removed the navigation should
>+    # not timeout. Switch to the target context, and wait until the expected
>+    # element is available.
>+    if target == "_parent":
>+        session.switch_frame("parent")
>+    elif target == "_top":
>+        session.switch_frame(None)
>+
>+    wait = Poll(
>+        session,
>+        timeout=5,
>+        ignored_exceptions=NoSuchElementException,
>+        message="Expected element has not been found")
>+    wait.until(lambda s: s.find.css("#foo"))
>+
>+
>+# Capability needed as long as no valid certificate is available:
>+#   https://github.com/web-platform-tests/wpt/issues/28847
>+@pytest.mark.capabilities({"acceptInsecureCerts": True})
>+def test_link_cross_origin(session, inline, url):
>+    base_path = ("/webdriver/tests/support/html/subframe.html" +
>+                 "?pipe=header(Cross-Origin-Opener-Policy,same-origin")
>+    target_page = url(base_path, protocol="https", domain="alt")
>+
>+    session.url = inline("<a href='{}'>click me</a>".format(target_page), protocol="https")
>+    link = session.find.css("a", all=False)
>+
>+    response = element_click(session, link)
>+    assert_success(response)
>+
>+    assert session.url == target_page
>+
>+    session.find.css("#delete", all=False)
> 
> 
>-def test_link_closes_window(session):
>+def test_link_closes_window(session, inline):
>     new_handle = session.new_window()
>     session.window_handle = new_handle
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/scroll_into_view.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/scroll_into_view.py
>index 4b026e986a21..c2dc6485286e 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/scroll_into_view.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/scroll_into_view.py
>@@ -2,7 +2,7 @@ import pytest
> 
> from tests.support.asserts import assert_error, assert_success
> from tests.support.helpers import center_point
>-from tests.support.inline import inline
>+
> 
> def element_click(session, element):
>     return session.transport.send(
>@@ -18,7 +18,7 @@ def assert_one_click(session):
>     return tuple(clicks[0])
> 
> 
>-def test_scroll_into_view(session):
>+def test_scroll_into_view(session, inline):
>     session.url = inline("""
>         <input type=text value=Federer
>         style="position: absolute; left: 0vh; top: 500vh">""")
>@@ -38,7 +38,7 @@ def test_scroll_into_view(session):
> 
> 
> @pytest.mark.parametrize("offset", range(9, 0, -1))
>-def test_partially_visible_does_not_scroll(session, offset):
>+def test_partially_visible_does_not_scroll(session, offset, inline):
>     session.url = inline("""
>         <style>
>         body {{
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/select.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/select.py
>index dcf92e645894..62d40755b59b 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/select.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/select.py
>@@ -1,7 +1,4 @@
>-from tests.support.inline import inline
>-
>-
>-def test_click_option(session):
>+def test_click_option(session, inline):
>     session.url = inline("""
>       <select>
>         <option>first
>@@ -17,7 +14,7 @@ def test_click_option(session):
>     assert not options[0].selected
> 
> 
>-def test_click_multiple_option(session):
>+def test_click_multiple_option(session, inline):
>     session.url = inline("""
>       <select multiple>
>         <option>first
>@@ -33,7 +30,7 @@ def test_click_multiple_option(session):
>     assert not options[1].selected
> 
> 
>-def test_click_preselected_option(session):
>+def test_click_preselected_option(session, inline):
>     session.url = inline("""
>       <select>
>         <option>first
>@@ -53,7 +50,7 @@ def test_click_preselected_option(session):
>     assert not options[1].selected
> 
> 
>-def test_click_preselected_multiple_option(session):
>+def test_click_preselected_multiple_option(session, inline):
>     session.url = inline("""
>       <select multiple>
>         <option>first
>@@ -73,7 +70,7 @@ def test_click_preselected_multiple_option(session):
>     assert not options[1].selected
> 
> 
>-def test_click_deselects_others(session):
>+def test_click_deselects_others(session, inline):
>     session.url = inline("""
>       <select>
>         <option>first
>@@ -92,7 +89,7 @@ def test_click_deselects_others(session):
>     assert options[0].selected
> 
> 
>-def test_click_multiple_does_not_deselect_others(session):
>+def test_click_multiple_does_not_deselect_others(session, inline):
>     session.url = inline("""
>       <select multiple>
>         <option>first
>@@ -112,7 +109,7 @@ def test_click_multiple_does_not_deselect_others(session):
>     assert options[2].selected
> 
> 
>-def test_click_selected_option(session):
>+def test_click_selected_option(session, inline):
>     session.url = inline("""
>       <select>
>         <option>first
>@@ -130,7 +127,7 @@ def test_click_selected_option(session):
>     assert options[1].selected
> 
> 
>-def test_click_selected_multiple_option(session):
>+def test_click_selected_multiple_option(session, inline):
>     session.url = inline("""
>       <select multiple>
>         <option>first
>@@ -152,7 +149,7 @@ def test_click_selected_multiple_option(session):
>     assert not options[1].selected
> 
> 
>-def test_out_of_view_dropdown(session):
>+def test_out_of_view_dropdown(session, inline):
>     session.url = inline("""
>       <select>
>         <option>1
>@@ -182,7 +179,7 @@ def test_out_of_view_dropdown(session):
>     assert options[14].selected
> 
> 
>-def test_out_of_view_multiple(session):
>+def test_out_of_view_multiple(session, inline):
>     session.url = inline("""
>       <select multiple>
>         <option>1
>@@ -213,7 +210,7 @@ def test_out_of_view_multiple(session):
>     assert last_option.selected
> 
> 
>-def test_option_disabled(session):
>+def test_option_disabled(session, inline):
>     session.url = inline("""
>         <select>
>           <option disabled>foo
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/shadow_dom.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/shadow_dom.py
>index b52f27429c19..45493b730d69 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/shadow_dom.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/shadow_dom.py
>@@ -1,6 +1,5 @@
>-from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> import pytest
>+from tests.support.asserts import assert_error, assert_success
> 
> 
> def element_click(session, element):
>@@ -10,7 +9,8 @@ def element_click(session, element):
>             element_id=element.id))
> 
> 
>-def get_checkbox_dom():
>+@pytest.fixture
>+def get_checkbox_dom(inline):
>     return inline("""
>         <style>
>             custom-checkbox-element {
>@@ -32,8 +32,8 @@ def get_checkbox_dom():
> 
> 
> @pytest.mark.parametrize("click_on", ["custom_element", "checkbox_element"])
>-def test_shadow_element_click(session, click_on):
>-    session.url = get_checkbox_dom()
>+def test_shadow_element_click(session, get_checkbox_dom, click_on):
>+    session.url = get_checkbox_dom
>     custom_element = session.find.css("custom-checkbox-element", all=False)
>     checkbox_element = session.execute_script("return arguments[0].shadowRoot.querySelector('input')",
>                                               args=(custom_element,))
>@@ -47,7 +47,8 @@ def test_shadow_element_click(session, click_on):
>     assert is_post_checked == True
> 
> 
>-def get_nested_shadow_checkbox_dom():
>+@pytest.fixture
>+def get_nested_shadow_checkbox_dom(inline):
>     return inline("""
>         <style>
>             custom-nesting-element {
>@@ -83,8 +84,8 @@ def get_nested_shadow_checkbox_dom():
> 
> 
> @pytest.mark.parametrize("click_on", ["outer_element", "inner_element", "checkbox_element"])
>-def test_nested_shadow_element_click(session, click_on):
>-    session.url = get_nested_shadow_checkbox_dom()
>+def test_nested_shadow_element_click(session, get_nested_shadow_checkbox_dom, click_on):
>+    session.url = get_nested_shadow_checkbox_dom
>     outer_element = session.find.css("custom-nesting-element", all=False)
>     inner_element = session.execute_script("return arguments[0].shadowRoot.querySelector('custom-checkbox-element')",
>                                            args=(outer_element,))
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/stale.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/stale.py
>index cd24dd70603d..8d2ae348ef4f 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/stale.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/stale.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_error
>-from tests.support.inline import inline
> 
> 
> def element_click(session, element):
>@@ -9,7 +8,7 @@ def element_click(session, element):
>             element_id=element.id))
> 
> 
>-def test_is_stale(session):
>+def test_is_stale(session, inline):
>     session.url = inline("<button>foo</button>")
>     button = session.find.css("button", all=False)
>     session.url = inline("<button>bar</button>")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/support/test_click_wdspec.html b/WebDriverTests/imported/w3c/webdriver/tests/element_click/support/test_click_wdspec.html
>new file mode 100644
>index 000000000000..a9451ec82bec
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/support/test_click_wdspec.html
>@@ -0,0 +1,100 @@
>+<!doctype html>
>+<meta charset=utf-8>
>+<html>
>+<head>
>+    <title>Test Element Click</title>
>+    <style>
>+      div { padding:0px; margin: 0px; }
>+      #trackPointer { position: fixed; }
>+      #resultContainer { width: 600px; height: 60px; }
>+      .area { width: 100px; height: 50px; background-color: #ccc; }
>+      .block { width: 5px; height: 5px; border: solid 1px red; }
>+    </style>
>+    <script>
>+        "use strict";
>+        var els = {};
>+        var allEvents = { events: [] };
>+        function displayMessage(message) {
>+            document.getElementById("events").innerHTML = "<p>" + message + "</p>";
>+        }
>+
>+        function appendMessage(message) {
>+            document.getElementById("events").innerHTML += "<p>" + message + "</p>";
>+        }
>+
>+        function recordPointerEvent(event) {
>+          if (event.type === "contextmenu") {
>+            event.preventDefault();
>+          }
>+          allEvents.events.push({
>+            "type": event.type,
>+            "button": event.button,
>+            "buttons": event.buttons,
>+            "pageX": event.pageX,
>+            "pageY": event.pageY,
>+            "ctrlKey": event.ctrlKey,
>+            "metaKey": event.metaKey,
>+            "altKey": event.altKey,
>+            "shiftKey": event.shiftKey,
>+            "target": event.target.id
>+          });
>+          appendMessage(event.type + " " +
>+              "button: " + event.button + ", " +
>+              "pageX: " + event.pageX + ", " +
>+              "pageY: " + event.pageY + ", " +
>+              "button: " + event.button + ", " +
>+              "buttons: " + event.buttons + ", " +
>+              "ctrlKey: " + event.ctrlKey + ", " +
>+              "altKey: " + event.altKey + ", " +
>+              "metaKey: " + event.metaKey + ", " +
>+              "shiftKey: " + event.shiftKey + ", " +
>+              "target id: " + event.target.id);
>+        }
>+
>+        function recordFirstPointerMove(event) {
>+          recordPointerEvent(event);
>+          window.removeEventListener("mousemove", recordFirstPointerMove);
>+        }
>+
>+        function resetEvents() {
>+          allEvents.events.length = 0;
>+          displayMessage("");
>+        }
>+
>+        function move(el, offsetX, offsetY, timeout) {
>+          return function(event) {
>+            setTimeout(function() {
>+              el.style.top = event.clientY + offsetY + "px";
>+              el.style.left = event.clientX + offsetX + "px";
>+            }, timeout);
>+          };
>+        }
>+
>+        document.addEventListener("DOMContentLoaded", function() {
>+          var outer = document.getElementById("outer");
>+          window.addEventListener("mousemove", recordFirstPointerMove);
>+          outer.addEventListener("click", recordPointerEvent);
>+          outer.addEventListener("dblclick", recordPointerEvent);
>+          outer.addEventListener("mousedown", recordPointerEvent);
>+          outer.addEventListener("mouseup", recordPointerEvent);
>+          outer.addEventListener("contextmenu", recordPointerEvent);
>+
>+          //visual cue for mousemove
>+          var pointer = document.getElementById("trackPointer");
>+          window.addEventListener("mousemove", move(pointer, 15, 15, 30));
>+        });
>+    </script>
>+</head>
>+<body>
>+  <div id="trackPointer" class="block"></div>
>+  <div>
>+    <h2>ClickReporter</h2>
>+    <div id="outer" class="area">
>+    </div>
>+  </div>
>+  <div id="resultContainer">
>+    <h2>Events</h2>
>+    <div id="events"></div>
>+  </div>
>+</body>
>+</html>
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_click/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/element_click/user_prompts.py
>index b3706fe4af16..140aceb3cedf 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_click/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_click/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def element_click(session, element):
>@@ -14,7 +13,7 @@ def element_click(session, element):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input type=text>")
>         element = session.find.css("input", all=False)
>@@ -32,7 +31,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input type=text>")
>         element = session.find.css("input", all=False)
>@@ -50,7 +49,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input type=text>")
>         element = session.find.css("input", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/content_editable.py b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/content_editable.py
>index 16ebc2d018fb..7f628f96a53a 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/content_editable.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/content_editable.py
>@@ -1,9 +1,4 @@
>-import pytest
>-
>-from tests.support.inline import inline
>-
>-
>-def test_sets_insertion_point_to_end(session):
>+def test_sets_insertion_point_to_end(session, inline):
>     session.url = inline('<div contenteditable=true>Hello,</div>')
>     input = session.find.css("div", all=False)
>     input.send_keys(' world!')
>@@ -15,7 +10,7 @@ def test_sets_insertion_point_to_end(session):
> #
> # 13. Set the text insertion caret using set selection range using current
> #     text length for both the start and end parameters.
>-def test_sets_insertion_point_to_after_last_text_node(session):
>+def test_sets_insertion_point_to_after_last_text_node(session, inline):
>     session.url = inline('<div contenteditable=true>Hel<span>lo</span>,</div>')
>     input = session.find.css("div", all=False)
>     input.send_keys(" world!")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/events.py b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/events.py
>index 41b00ef37fa2..4be1432bf3c2 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/events.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/events.py
>@@ -5,7 +5,6 @@ from tests.support.asserts import (
>     assert_events_equal,
>     assert_success,
> )
>-from tests.support.inline import inline
> 
> from . import map_files_to_multiline_text
> 
>@@ -31,7 +30,7 @@ def element_send_keys(session, element, text):
>         {"text": text})
> 
> 
>-def test_file_upload(session, create_files, add_event_listeners, tracked_events):
>+def test_file_upload(session, create_files, add_event_listeners, tracked_events, inline):
>     expected_events = [
>         "input",
>         "change",
>@@ -50,7 +49,7 @@ def test_file_upload(session, create_files, add_event_listeners, tracked_events)
> 
> 
> @pytest.mark.parametrize("tag", ["input", "textarea"])
>-def test_form_control_send_text(session, add_event_listeners, tracked_events, tag):
>+def test_form_control_send_text(session, add_event_listeners, tracked_events, inline, tag):
>     expected_events = [
>         "focus",
>         "keydown",
>@@ -77,7 +76,7 @@ def test_form_control_send_text(session, add_event_listeners, tracked_events, ta
> 
> 
> @pytest.mark.parametrize("tag", ["input", "textarea"])
>-def test_not_blurred(session, tag):
>+def test_not_blurred(session, inline, tag):
>     session.url = inline("<%s>" % tag)
>     element = session.find.css(tag, all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/file_upload.py b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/file_upload.py
>index 7fbab8a66aa4..ef792f4dd855 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/file_upload.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/file_upload.py
>@@ -1,7 +1,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_files_uploaded, assert_success
>-from tests.support.inline import inline
> 
> from . import map_files_to_multiline_text
> 
>@@ -14,7 +13,7 @@ def element_send_keys(session, element, text):
>         {"text": text})
> 
> 
>-def test_empty_text(session):
>+def test_empty_text(session, inline):
>     session.url = inline("<input type=file>")
>     element = session.find.css("input", all=False)
> 
>@@ -22,7 +21,7 @@ def test_empty_text(session):
>     assert_error(response, "invalid argument")
> 
> 
>-def test_multiple_files(session, create_files):
>+def test_multiple_files(session, create_files, inline):
>     files = create_files(["foo", "bar"])
> 
>     session.url = inline("<input type=file multiple>")
>@@ -35,7 +34,7 @@ def test_multiple_files(session, create_files):
>     assert_files_uploaded(session, element, files)
> 
> 
>-def test_multiple_files_last_path_not_found(session, create_files):
>+def test_multiple_files_last_path_not_found(session, create_files, inline):
>     files = create_files(["foo", "bar"])
>     files.append("foo bar")
> 
>@@ -49,7 +48,7 @@ def test_multiple_files_last_path_not_found(session, create_files):
>     assert_files_uploaded(session, element, [])
> 
> 
>-def test_multiple_files_without_multiple_attribute(session, create_files):
>+def test_multiple_files_without_multiple_attribute(session, create_files, inline):
>     files = create_files(["foo", "bar"])
> 
>     session.url = inline("<input type=file>")
>@@ -62,7 +61,7 @@ def test_multiple_files_without_multiple_attribute(session, create_files):
>     assert_files_uploaded(session, element, [])
> 
> 
>-def test_multiple_files_send_twice(session, create_files):
>+def test_multiple_files_send_twice(session, create_files, inline):
>     first_files = create_files(["foo", "bar"])
>     second_files = create_files(["john", "doe"])
> 
>@@ -80,7 +79,7 @@ def test_multiple_files_send_twice(session, create_files):
>     assert_files_uploaded(session, element, first_files + second_files)
> 
> 
>-def test_multiple_files_reset_with_element_clear(session, create_files):
>+def test_multiple_files_reset_with_element_clear(session, create_files, inline):
>     first_files = create_files(["foo", "bar"])
>     second_files = create_files(["john", "doe"])
> 
>@@ -102,7 +101,7 @@ def test_multiple_files_reset_with_element_clear(session, create_files):
>     assert_files_uploaded(session, element, second_files)
> 
> 
>-def test_single_file(session, create_files):
>+def test_single_file(session, create_files, inline):
>     files = create_files(["foo"])
> 
>     session.url = inline("<input type=file>")
>@@ -114,7 +113,7 @@ def test_single_file(session, create_files):
>     assert_files_uploaded(session, element, files)
> 
> 
>-def test_single_file_replaces_without_multiple_attribute(session, create_files):
>+def test_single_file_replaces_without_multiple_attribute(session, create_files, inline):
>     files = create_files(["foo", "bar"])
> 
>     session.url = inline("<input type=file>")
>@@ -129,7 +128,7 @@ def test_single_file_replaces_without_multiple_attribute(session, create_files):
>     assert_files_uploaded(session, element, [files[1]])
> 
> 
>-def test_single_file_appends_with_multiple_attribute(session, create_files):
>+def test_single_file_appends_with_multiple_attribute(session, create_files, inline):
>     files = create_files(["foo", "bar"])
> 
>     session.url = inline("<input type=file multiple>")
>@@ -144,7 +143,7 @@ def test_single_file_appends_with_multiple_attribute(session, create_files):
>     assert_files_uploaded(session, element, files)
> 
> 
>-def test_transparent(session, create_files):
>+def test_transparent(session, create_files, inline):
>     files = create_files(["foo"])
>     session.url = inline("""<input type=file style="opacity: 0">""")
>     element = session.find.css("input", all=False)
>@@ -154,7 +153,7 @@ def test_transparent(session, create_files):
>     assert_files_uploaded(session, element, files)
> 
> 
>-def test_obscured(session, create_files):
>+def test_obscured(session, create_files, inline):
>     files = create_files(["foo"])
>     session.url = inline("""
>         <style>
>@@ -178,7 +177,7 @@ def test_obscured(session, create_files):
>     assert_files_uploaded(session, element, files)
> 
> 
>-def test_outside_viewport(session, create_files):
>+def test_outside_viewport(session, create_files, inline):
>     files = create_files(["foo"])
>     session.url = inline("""<input type=file style="margin-left: -100vh">""")
>     element = session.find.css("input", all=False)
>@@ -188,7 +187,7 @@ def test_outside_viewport(session, create_files):
>     assert_files_uploaded(session, element, files)
> 
> 
>-def test_hidden(session, create_files):
>+def test_hidden(session, create_files, inline):
>     files = create_files(["foo"])
>     session.url = inline("<input type=file hidden>")
>     element = session.find.css("input", all=False)
>@@ -198,7 +197,7 @@ def test_hidden(session, create_files):
>     assert_files_uploaded(session, element, files)
> 
> 
>-def test_display_none(session, create_files):
>+def test_display_none(session, create_files, inline):
>     files = create_files(["foo"])
>     session.url = inline("""<input type=file style="display: none">""")
>     element = session.find.css("input", all=False)
>@@ -209,7 +208,7 @@ def test_display_none(session, create_files):
> 
> 
> @pytest.mark.capabilities({"strictFileInteractability": True})
>-def test_strict_hidden(session, create_files):
>+def test_strict_hidden(session, create_files, inline):
>     files = create_files(["foo"])
>     session.url = inline("<input type=file hidden>")
>     element = session.find.css("input", all=False)
>@@ -219,7 +218,7 @@ def test_strict_hidden(session, create_files):
> 
> 
> @pytest.mark.capabilities({"strictFileInteractability": True})
>-def test_strict_display_none(session, create_files):
>+def test_strict_display_none(session, create_files, inline):
>     files = create_files(["foo"])
>     session.url = inline("""<input type=file style="display: none">""")
>     element = session.find.css("input", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/form_controls.py b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/form_controls.py
>index e53d0610f1ed..0403dc92372e 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/form_controls.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/form_controls.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_element_has_focus
>-from tests.support.inline import inline
> 
> 
> def element_send_keys(session, element, text):
>@@ -10,7 +9,7 @@ def element_send_keys(session, element, text):
>         {"text": text})
> 
> 
>-def test_input(session):
>+def test_input(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
>     assert element.property("value") == ""
>@@ -20,7 +19,7 @@ def test_input(session):
>     assert_element_has_focus(element)
> 
> 
>-def test_textarea(session):
>+def test_textarea(session, inline):
>     session.url = inline("<textarea>")
>     element = session.find.css("textarea", all=False)
>     assert element.property("value") == ""
>@@ -30,7 +29,7 @@ def test_textarea(session):
>     assert_element_has_focus(element)
> 
> 
>-def test_input_append(session):
>+def test_input_append(session, inline):
>     session.url = inline("<input value=a>")
>     element = session.find.css("input", all=False)
>     assert element.property("value") == "a"
>@@ -42,7 +41,7 @@ def test_input_append(session):
>     assert element.property("value") == "abc"
> 
> 
>-def test_textarea_append(session):
>+def test_textarea_append(session, inline):
>     session.url = inline("<textarea>a</textarea>")
>     element = session.find.css("textarea", all=False)
>     assert element.property("value") == "a"
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/interactability.py b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/interactability.py
>index 0717537ae5d8..273843fb7b46 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/interactability.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/interactability.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import iframe, inline
> 
> 
> def element_send_keys(session, element, text):
>@@ -10,7 +9,7 @@ def element_send_keys(session, element, text):
>         {"text": text})
> 
> 
>-def test_body_is_interactable(session):
>+def test_body_is_interactable(session, inline):
>     session.url = inline("""
>         <body onkeypress="document.querySelector('input').value += event.key">
>           <input>
>@@ -29,7 +28,7 @@ def test_body_is_interactable(session):
>     assert result.property("value") == "foo"
> 
> 
>-def test_document_element_is_interactable(session):
>+def test_document_element_is_interactable(session, inline):
>     session.url = inline("""
>         <html onkeypress="document.querySelector('input').value += event.key">
>           <input>
>@@ -49,7 +48,7 @@ def test_document_element_is_interactable(session):
>     assert result.property("value") == "foo"
> 
> 
>-def test_iframe_is_interactable(session):
>+def test_iframe_is_interactable(session, inline, iframe):
>     session.url = inline(iframe("""
>         <body onkeypress="document.querySelector('input').value += event.key">
>           <input>
>@@ -73,7 +72,7 @@ def test_iframe_is_interactable(session):
>     assert result.property("value") == "foo"
> 
> 
>-def test_transparent_element(session):
>+def test_transparent_element(session, inline):
>     session.url = inline("""<input style="opacity: 0">""")
>     element = session.find.css("input", all=False)
> 
>@@ -82,7 +81,7 @@ def test_transparent_element(session):
>     assert element.property("value") == "foo"
> 
> 
>-def test_readonly_element(session):
>+def test_readonly_element(session, inline):
>     session.url = inline("<input readonly>")
>     element = session.find.css("input", all=False)
> 
>@@ -91,7 +90,7 @@ def test_readonly_element(session):
>     assert element.property("value") == ""
> 
> 
>-def test_obscured_element(session):
>+def test_obscured_element(session, inline):
>     session.url = inline("""
>       <input>
>       <div style="position: relative; top: -3em; height: 5em; background: blue;"></div>
>@@ -103,7 +102,7 @@ def test_obscured_element(session):
>     assert element.property("value") == "foo"
> 
> 
>-def test_not_a_focusable_element(session):
>+def test_not_a_focusable_element(session, inline):
>     session.url = inline("<div>foo</div>")
>     element = session.find.css("div", all=False)
> 
>@@ -111,7 +110,7 @@ def test_not_a_focusable_element(session):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_display_none(session):
>+def test_display_none(session, inline):
>     session.url = inline("""<input style="display: none">""")
>     element = session.find.css("input", all=False)
> 
>@@ -119,7 +118,7 @@ def test_display_none(session):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_visibility_hidden(session):
>+def test_visibility_hidden(session, inline):
>     session.url = inline("""<input style="visibility: hidden">""")
>     element = session.find.css("input", all=False)
> 
>@@ -127,7 +126,7 @@ def test_visibility_hidden(session):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_hidden(session):
>+def test_hidden(session, inline):
>     session.url = inline("<input hidden>")
>     element = session.find.css("input", all=False)
> 
>@@ -135,7 +134,7 @@ def test_hidden(session):
>     assert_error(response, "element not interactable")
> 
> 
>-def test_disabled(session):
>+def test_disabled(session, inline):
>     session.url = inline("""<input disabled>""")
>     element = session.find.css("input", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/scroll_into_view.py b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/scroll_into_view.py
>index 18f87ffaaec6..205c4e30e1ed 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/scroll_into_view.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/scroll_into_view.py
>@@ -1,6 +1,6 @@
> from tests.support.asserts import assert_success
> from tests.support.helpers import is_element_in_viewport
>-from tests.support.inline import inline
>+
> 
> def element_send_keys(session, element, text):
>     return session.transport.send(
>@@ -10,7 +10,7 @@ def element_send_keys(session, element, text):
>         {"text": text})
> 
> 
>-def test_element_outside_of_not_scrollable_viewport(session):
>+def test_element_outside_of_not_scrollable_viewport(session, inline):
>     session.url = inline("<input style=\"position: relative; left: -9999px;\">")
>     element = session.find.css("input", all=False)
> 
>@@ -20,7 +20,7 @@ def test_element_outside_of_not_scrollable_viewport(session):
>     assert not is_element_in_viewport(session, element)
> 
> 
>-def test_element_outside_of_scrollable_viewport(session):
>+def test_element_outside_of_scrollable_viewport(session, inline):
>     session.url = inline("<input style=\"margin-top: 102vh;\">")
>     element = session.find.css("input", all=False)
> 
>@@ -30,7 +30,7 @@ def test_element_outside_of_scrollable_viewport(session):
>     assert is_element_in_viewport(session, element)
> 
> 
>-def test_option_select_container_outside_of_scrollable_viewport(session):
>+def test_option_select_container_outside_of_scrollable_viewport(session, inline):
>     session.url = inline("""
>         <select style="margin-top: 102vh;">
>           <option value="foo">foo</option>
>@@ -47,7 +47,7 @@ def test_option_select_container_outside_of_scrollable_viewport(session):
>     assert is_element_in_viewport(session, element)
> 
> 
>-def test_option_stays_outside_of_scrollable_viewport(session):
>+def test_option_stays_outside_of_scrollable_viewport(session, inline):
>     session.url = inline("""
>         <select multiple style="height: 105vh; margin-top: 100vh;">
>           <option value="foo" id="foo" style="height: 100vh;">foo</option>
>@@ -66,7 +66,7 @@ def test_option_stays_outside_of_scrollable_viewport(session):
>     assert not is_element_in_viewport(session, option_bar)
> 
> 
>-def test_contenteditable_element_outside_of_scrollable_viewport(session):
>+def test_contenteditable_element_outside_of_scrollable_viewport(session, inline):
>     session.url = inline("<div contenteditable style=\"margin-top: 102vh;\"></div>")
>     element = session.find.css("div", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/send_keys.py b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/send_keys.py
>index edf91e776148..aa393e16d814 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/send_keys.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/send_keys.py
>@@ -4,7 +4,6 @@ from webdriver import Element
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def element_send_keys(session, element, text):
>@@ -15,7 +14,7 @@ def element_send_keys(session, element, text):
>         {"text": text})
> 
> 
>-def test_null_parameter_value(session, http):
>+def test_null_parameter_value(session, http, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>@@ -25,7 +24,7 @@ def test_null_parameter_value(session, http):
>         assert_error(Response.from_http(response), "invalid argument")
> 
> 
>-def test_null_response_value(session):
>+def test_null_response_value(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>@@ -36,10 +35,17 @@ def test_null_response_value(session):
> 
> def test_no_top_browsing_context(session, closed_window):
>     element = Element("foo", session)
>+    response = element_send_keys(session, element, "foo")
>+    assert_error(response, "no such window")
> 
>+    original_handle, element = closed_window
>     response = element_send_keys(session, element, "foo")
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = element_send_keys(session, element, "foo")
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     element = Element("foo", session)
>@@ -49,7 +55,7 @@ def test_no_browsing_context(session, closed_frame):
> 
> 
> @pytest.mark.parametrize("value", [True, None, 1, [], {}])
>-def test_invalid_text_type(session, value):
>+def test_invalid_text_type(session, inline, value):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>@@ -57,7 +63,7 @@ def test_invalid_text_type(session, value):
>     assert_error(response, "invalid argument")
> 
> 
>-def test_stale_element(session):
>+def test_stale_element(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/user_prompts.py
>index 621bdffa6642..c1046840fa4e 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/element_send_keys/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def element_send_keys(session, element, text):
>@@ -15,7 +14,7 @@ def element_send_keys(session, element, text):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input type=text>")
>         element = session.find.css("input", all=False)
>@@ -33,7 +32,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input type=text>")
>         element = session.find.css("input", all=False)
>@@ -51,7 +50,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input type=text>")
>         element = session.find.css("input", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/collections.py b/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/collections.py
>index 484a247cffd9..2dc9b9a009ac 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/collections.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/collections.py
>@@ -1,9 +1,6 @@
> import os
> 
>-from six import text_type
>-
> from tests.support.asserts import assert_same_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def execute_async_script(session, script, args=None):
>@@ -35,7 +32,7 @@ def test_array(session):
>     assert_success(response, [1, 2])
> 
> 
>-def test_file_list(session, tmpdir):
>+def test_file_list(session, tmpdir, inline):
>     files = [tmpdir.join("foo.txt"), tmpdir.join("bar.txt")]
> 
>     session.url = inline("<input type=file multiple>")
>@@ -54,11 +51,11 @@ def test_file_list(session, tmpdir):
>     for expected, actual in zip(files, value):
>         assert isinstance(actual, dict)
>         assert "name" in actual
>-        assert isinstance(actual["name"], text_type)
>+        assert isinstance(actual["name"], str)
>         assert os.path.basename(str(expected)) == actual["name"]
> 
> 
>-def test_html_all_collection(session):
>+def test_html_all_collection(session, inline):
>     session.url = inline("""
>         <p>foo
>         <p>bar
>@@ -86,7 +83,7 @@ def test_html_all_collection(session):
>     assert_same_element(session, ps[1], value[5])
> 
> 
>-def test_html_collection(session):
>+def test_html_collection(session, inline):
>     session.url = inline("""
>         <p>foo
>         <p>bar
>@@ -104,7 +101,7 @@ def test_html_collection(session):
>         assert_same_element(session, expected, actual)
> 
> 
>-def test_html_form_controls_collection(session):
>+def test_html_form_controls_collection(session, inline):
>     session.url = inline("""
>         <form>
>             <input>
>@@ -124,7 +121,7 @@ def test_html_form_controls_collection(session):
>         assert_same_element(session, expected, actual)
> 
> 
>-def test_html_options_collection(session):
>+def test_html_options_collection(session, inline):
>     session.url = inline("""
>         <select>
>             <option>
>@@ -144,7 +141,7 @@ def test_html_options_collection(session):
>         assert_same_element(session, expected, actual)
> 
> 
>-def test_node_list(session):
>+def test_node_list(session, inline):
>     session.url = inline("""
>         <p>foo
>         <p>bar
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/execute_async.py b/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/execute_async.py
>index c769ca811ee0..5746ed6f05f3 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/execute_async.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/execute_async.py
>@@ -1,8 +1,10 @@
> import pytest
> 
>+from webdriver.error import NoSuchAlertException
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_success
>+from tests.support.sync import Poll
> 
> 
> def execute_async_script(session, script, args=None):
>@@ -50,9 +52,16 @@ def test_abort_by_user_prompt_twice(session, dialog_type):
> 
>     session.alert.accept()
> 
>-    # The first alert has been accepted by the user prompt handler, the second one remains.
>-    # FIXME: this is how browsers currently work, but the spec should clarify if this is the
>-    #        expected behavior, see https://github.com/w3c/webdriver/issues/1153.
>-    assert session.alert.text == "Bye"
>+    # The first alert has been accepted by the user prompt handler, the second
>+    # alert will still be opened because the current step isn't aborted.
>+    wait = Poll(
>+        session,
>+        timeout=5,
>+        message="Second alert has not been opened",
>+        ignored_exceptions=NoSuchAlertException
>+    )
>+    text = wait.until(lambda s: s.alert.text)
>+
>+    assert text == "Bye"
> 
>     session.alert.accept()
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/properties.py b/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/properties.py
>index 394ae3294cd3..e51b3e3ea579 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/properties.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/execute_async_script/properties.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_same_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def execute_async_script(session, script, args=None):
>@@ -11,7 +10,7 @@ def execute_async_script(session, script, args=None):
>         body)
> 
> 
>-def test_content_attribute(session):
>+def test_content_attribute(session, inline):
>     session.url = inline("<input value=foobar>")
>     response = execute_async_script(session, """
>         const resolve = arguments[0];
>@@ -21,7 +20,7 @@ def test_content_attribute(session):
>     assert_success(response, "foobar")
> 
> 
>-def test_idl_attribute(session):
>+def test_idl_attribute(session, inline):
>     session.url = inline("""
>         <input>
>         <script>
>@@ -37,7 +36,7 @@ def test_idl_attribute(session):
>     assert_success(response, "foobar")
> 
> 
>-def test_idl_attribute_element(session):
>+def test_idl_attribute_element(session, inline):
>     session.url = inline("""
>         <p>foo
>         <p>bar
>@@ -59,7 +58,7 @@ def test_idl_attribute_element(session):
>     assert_same_element(session, bar, value)
> 
> 
>-def test_script_defining_property(session):
>+def test_script_defining_property(session, inline):
>     session.url = inline("<input>")
>     session.execute_script("""
>         const input = document.querySelector("input");
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/execute_script/collections.py b/WebDriverTests/imported/w3c/webdriver/tests/execute_script/collections.py
>index be0b3a018c50..8291fd71388b 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/execute_script/collections.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/execute_script/collections.py
>@@ -1,9 +1,6 @@
> import os
> 
>-from six import text_type
>-
> from tests.support.asserts import assert_same_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def execute_script(session, script, args=None):
>@@ -31,7 +28,7 @@ def test_array(session):
>     assert_success(response, [1, 2])
> 
> 
>-def test_file_list(session, tmpdir):
>+def test_file_list(session, tmpdir, inline):
>     files = [tmpdir.join("foo.txt"), tmpdir.join("bar.txt")]
> 
>     session.url = inline("<input type=file multiple>")
>@@ -47,11 +44,11 @@ def test_file_list(session, tmpdir):
>     for expected, actual in zip(files, value):
>         assert isinstance(actual, dict)
>         assert "name" in actual
>-        assert isinstance(actual["name"], text_type)
>+        assert isinstance(actual["name"], str)
>         assert os.path.basename(str(expected)) == actual["name"]
> 
> 
>-def test_html_all_collection(session):
>+def test_html_all_collection(session, inline):
>     session.url = inline("""
>         <p>foo
>         <p>bar
>@@ -76,7 +73,7 @@ def test_html_all_collection(session):
>     assert_same_element(session, ps[1], value[5])
> 
> 
>-def test_html_collection(session):
>+def test_html_collection(session, inline):
>     session.url = inline("""
>         <p>foo
>         <p>bar
>@@ -91,7 +88,7 @@ def test_html_collection(session):
>         assert_same_element(session, expected, actual)
> 
> 
>-def test_html_form_controls_collection(session):
>+def test_html_form_controls_collection(session, inline):
>     session.url = inline("""
>         <form>
>             <input>
>@@ -108,7 +105,7 @@ def test_html_form_controls_collection(session):
>         assert_same_element(session, expected, actual)
> 
> 
>-def test_html_options_collection(session):
>+def test_html_options_collection(session, inline):
>     session.url = inline("""
>         <select>
>             <option>
>@@ -125,7 +122,7 @@ def test_html_options_collection(session):
>         assert_same_element(session, expected, actual)
> 
> 
>-def test_node_list(session):
>+def test_node_list(session, inline):
>     session.url = inline("""
>         <p>foo
>         <p>bar
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/execute_script/cyclic.py b/WebDriverTests/imported/w3c/webdriver/tests/execute_script/cyclic.py
>index 16bdcdd1dea5..e3094f89f3b7 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/execute_script/cyclic.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/execute_script/cyclic.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_error, assert_same_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def execute_script(session, script, args=None):
>@@ -49,7 +48,7 @@ def test_object_in_array(session):
>     assert_error(response, "javascript error")
> 
> 
>-def test_element_in_collection(session):
>+def test_element_in_collection(session, inline):
>     session.url = inline("<div></div>")
>     divs = session.find.css("div")
> 
>@@ -63,7 +62,7 @@ def test_element_in_collection(session):
>         assert_same_element(session, expected, actual)
> 
> 
>-def test_element_in_object(session):
>+def test_element_in_object(session, inline):
>     session.url = inline("<div></div>")
>     div = session.find.css("div", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/execute_script/execute.py b/WebDriverTests/imported/w3c/webdriver/tests/execute_script/execute.py
>index bd719b27859e..0f934cbb4450 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/execute_script/execute.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/execute_script/execute.py
>@@ -1,9 +1,9 @@
> import pytest
> 
>+from webdriver.error import NoSuchAlertException
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> from tests.support.sync import Poll
> 
> 
>@@ -34,7 +34,7 @@ def test_no_browsing_context(session, closed_frame):
>     assert_error(response, "no such window")
> 
> 
>-def test_opening_new_window_keeps_current_window_handle(session):
>+def test_opening_new_window_keeps_current_window_handle(session, inline):
>     original_handle = session.window_handle
>     original_handles = session.handles
> 
>@@ -57,7 +57,7 @@ def test_ending_comment(session):
>     assert_success(response, 1)
> 
> 
>-def test_override_listeners(session):
>+def test_override_listeners(session, inline):
>     session.url = inline("""
> <script>
> called = [];
>@@ -88,9 +88,16 @@ def test_abort_by_user_prompt_twice(session, dialog_type):
> 
>     session.alert.accept()
> 
>-    # The first alert has been accepted by the user prompt handler, the second one remains.
>-    # FIXME: this is how browsers currently work, but the spec should clarify if this is the
>-    #        expected behavior, see https://github.com/w3c/webdriver/issues/1153.
>-    assert session.alert.text == "Bye"
>+    # The first alert has been accepted by the user prompt handler, the second
>+    # alert will still be opened because the current step isn't aborted.
>+    wait = Poll(
>+        session,
>+        timeout=5,
>+        message="Second alert has not been opened",
>+        ignored_exceptions=NoSuchAlertException
>+    )
>+    text = wait.until(lambda s: s.alert.text)
>+
>+    assert text == "Bye"
> 
>     session.alert.accept()
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/execute_script/properties.py b/WebDriverTests/imported/w3c/webdriver/tests/execute_script/properties.py
>index 2be4f1f3ccc9..51999936e71a 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/execute_script/properties.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/execute_script/properties.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_same_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def execute_script(session, script, args=None):
>@@ -11,7 +10,7 @@ def execute_script(session, script, args=None):
>         body)
> 
> 
>-def test_content_attribute(session):
>+def test_content_attribute(session, inline):
>     session.url = inline("<input value=foobar>")
>     response = execute_script(session, """
>         const input = document.querySelector("input");
>@@ -20,7 +19,7 @@ def test_content_attribute(session):
>     assert_success(response, "foobar")
> 
> 
>-def test_idl_attribute(session):
>+def test_idl_attribute(session, inline):
>     session.url = inline("""
>         <input>
>         <script>
>@@ -35,7 +34,7 @@ def test_idl_attribute(session):
>     assert_success(response, "foobar")
> 
> 
>-def test_idl_attribute_element(session):
>+def test_idl_attribute_element(session, inline):
>     session.url = inline("""
>         <p>foo
>         <p>bar
>@@ -56,7 +55,7 @@ def test_idl_attribute_element(session):
>     assert_same_element(session, bar, value)
> 
> 
>-def test_script_defining_property(session):
>+def test_script_defining_property(session, inline):
>     session.url = inline("<input>")
>     execute_script(session, """
>         const input = document.querySelector("input");
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_element/find.py b/WebDriverTests/imported/w3c/webdriver/tests/find_element/find.py
>index 9f0911d56dc0..4510617da5a6 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/find_element/find.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_element/find.py
>@@ -3,7 +3,6 @@ import pytest
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_same_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def find_element(session, using, value):
>@@ -48,7 +47,7 @@ def test_invalid_selector_argument(session, value):
>                           ("partial link text", "link text"),
>                           ("tag name", "a"),
>                           ("xpath", "//a")])
>-def test_find_element(session, using, value):
>+def test_find_element(session, inline, using, value):
>     # Step 8 - 9
>     session.url = inline("<a href=# id=linkText>full link text</a>")
> 
>@@ -64,7 +63,7 @@ def test_find_element(session, using, value):
>     ("<a href=#>LINK TEXT</a>", "LINK TEXT"),
>     ("<a href=# style='text-transform: uppercase'>link text</a>", "LINK TEXT"),
> ])
>-def test_find_element_link_text(session, document, value):
>+def test_find_element_link_text(session, inline, document, value):
>     # Step 8 - 9
>     session.url = inline(document)
> 
>@@ -81,7 +80,7 @@ def test_find_element_link_text(session, document, value):
>     ("<a href=#>PARTIAL LINK TEXT</a>", "LINK"),
>     ("<a href=# style='text-transform: uppercase'>partial link text</a>", "LINK"),
> ])
>-def test_find_element_partial_link_text(session, document, value):
>+def test_find_element_partial_link_text(session, inline, document, value):
>     # Step 8 - 9
>     session.url = inline(document)
> 
>@@ -102,7 +101,7 @@ def test_no_element(session, using, value):
>                           ("partial link text", "link text"),
>                           ("tag name", "a"),
>                           ("xpath", "//*[name()='a']")])
>-def test_xhtml_namespace(session, using, value):
>+def test_xhtml_namespace(session, inline, using, value):
>     session.url = inline("""<a href="#" id="linkText">full link text</a>""",
>                          doctype="xhtml")
>     expected = session.execute_script("return document.links[0]")
>@@ -116,7 +115,7 @@ def test_xhtml_namespace(session, using, value):
>                          [("css selector", ":root"),
>                           ("tag name", "html"),
>                           ("xpath", "/html")])
>-def test_htmldocument(session, using, value):
>+def test_htmldocument(session, inline, using, value):
>     session.url = inline("")
>     response = find_element(session, using, value)
>     assert_success(response)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_element/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/find_element/user_prompts.py
>index 613466b62b51..ada8e8ebee33 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/find_element/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_element/user_prompts.py
>@@ -8,7 +8,6 @@ from tests.support.asserts import (
>     assert_success,
>     assert_dialog_handled,
> )
>-from tests.support.inline import inline
> 
> 
> def find_element(session, using, value):
>@@ -18,7 +17,7 @@ def find_element(session, using, value):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<p>bar</p>")
>         element = session.find.css("p", all=False)
>@@ -36,7 +35,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<p>bar</p>")
> 
>@@ -51,7 +50,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<p>bar</p>")
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_element/find.py b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_element/find.py
>index aa648117976b..879de3713f99 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_element/find.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_element/find.py
>@@ -3,7 +3,6 @@ import pytest
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_same_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def find_element(session, element_id, using, value):
>@@ -14,7 +13,7 @@ def find_element(session, element_id, using, value):
>         {"using": using, "value": value})
> 
> 
>-def test_null_parameter_value(session, http):
>+def test_null_parameter_value(session, http, inline):
>     session.url = inline("<div><a href=# id=linkText>full link text</a></div>")
>     element = session.find.css("div", all=False)
> 
>@@ -54,7 +53,7 @@ def test_invalid_selector_argument(session, value):
>                           ("partial link text", "link text"),
>                           ("tag name", "a"),
>                           ("xpath", "//a")])
>-def test_find_element(session, using, value):
>+def test_find_element(session, inline, using, value):
>     # Step 8 - 9
>     session.url = inline("<div><a href=# id=linkText>full link text</a></div>")
>     element = session.find.css("div", all=False)
>@@ -70,7 +69,7 @@ def test_find_element(session, using, value):
>     ("<a href=#>LINK TEXT</a>", "LINK TEXT"),
>     ("<a href=# style='text-transform: uppercase'>link text</a>", "LINK TEXT"),
> ])
>-def test_find_element_link_text(session, document, value):
>+def test_find_element_link_text(session, inline, document, value):
>     # Step 8 - 9
>     session.url = inline("<div>{0}</div>".format(document))
>     element = session.find.css("div", all=False)
>@@ -88,7 +87,7 @@ def test_find_element_link_text(session, document, value):
>     ("<a href=#>PARTIAL LINK TEXT</a>", "LINK"),
>     ("<a href=# style='text-transform: uppercase'>partial link text</a>", "LINK"),
> ])
>-def test_find_element_partial_link_text(session, document, value):
>+def test_find_element_partial_link_text(session, inline, document, value):
>     # Step 8 - 9
>     session.url = inline("<div>{0}</div>".format(document))
>     element = session.find.css("div", all=False)
>@@ -98,7 +97,7 @@ def test_find_element_partial_link_text(session, document, value):
> 
> 
> @pytest.mark.parametrize("using,value", [("css selector", "#wontExist")])
>-def test_no_element(session, using, value):
>+def test_no_element(session, inline, using, value):
>     # Step 8 - 9
>     session.url = inline("<div></div>")
>     element = session.find.css("div", all=False)
>@@ -112,7 +111,7 @@ def test_no_element(session, using, value):
>                           ("partial link text", "link text"),
>                           ("tag name", "a"),
>                           ("xpath", "//*[name()='a']")])
>-def test_xhtml_namespace(session, using, value):
>+def test_xhtml_namespace(session, inline, using, value):
>     session.url = inline("""<p><a href="#" id="linkText">full link text</a></p>""",
>                          doctype="xhtml")
>     from_element = session.execute_script("""return document.querySelector("p")""")
>@@ -123,7 +122,7 @@ def test_xhtml_namespace(session, using, value):
>     assert_same_element(session, value, expected)
> 
> 
>-def test_parent_htmldocument(session):
>+def test_parent_htmldocument(session, inline):
>     session.url = inline("")
>     from_element = session.execute_script("""return document.querySelector("body")""")
>     expected = session.execute_script("return document.documentElement")
>@@ -133,7 +132,7 @@ def test_parent_htmldocument(session):
>     assert_same_element(session, value, expected)
> 
> 
>-def test_parent_of_document_node_errors(session):
>+def test_parent_of_document_node_errors(session, inline):
>     session.url = inline("")
>     from_element = session.execute_script("return document.documentElement")
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_element/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_element/user_prompts.py
>index 3fdaf4e47ed7..0537a786189c 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_element/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_element/user_prompts.py
>@@ -8,7 +8,6 @@ from tests.support.asserts import (
>     assert_success,
>     assert_dialog_handled,
> )
>-from tests.support.inline import inline
> 
> 
> def find_element(session, element_id, using, value):
>@@ -20,7 +19,7 @@ def find_element(session, element_id, using, value):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<div><p>bar</p><div>")
>         outer_element = session.find.css("div", all=False)
>@@ -39,7 +38,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<div><p>bar</p><div>")
>         outer_element = session.find.css("div", all=False)
>@@ -55,7 +54,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<div><p>bar</p><div>")
>         outer_element = session.find.css("div", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_shadow_root/conftest.py b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_shadow_root/conftest.py
>new file mode 100644
>index 000000000000..b8fc93319f43
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_shadow_root/conftest.py
>@@ -0,0 +1,19 @@
>+import pytest
>+
>+@pytest.fixture
>+def get_shadow_page(inline):
>+    def get_shadow_page(shadow_content):
>+        return inline("""
>+            <custom-shadow-element></custom-shadow-element>
>+            <script>
>+                customElements.define('custom-shadow-element',
>+                    class extends HTMLElement {{
>+                        constructor() {{
>+                                super();
>+                                this.attachShadow({{mode: 'open'}}).innerHTML = `
>+                                    {{ {0} }}
>+                                `;
>+                            }}
>+                    }});
>+            </script>""".format(shadow_content))
>+    return get_shadow_page
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_shadow_root/find.py b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_shadow_root/find.py
>new file mode 100644
>index 000000000000..87941d495e13
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_shadow_root/find.py
>@@ -0,0 +1,141 @@
>+import pytest
>+
>+from webdriver.transport import Response
>+
>+from tests.support.asserts import assert_error, assert_same_element, assert_success
>+
>+
>+def find_element(session, shadow_id, using, value):
>+    return session.transport.send(
>+        "POST", "session/{session_id}/shadow/{shadow_id}/element".format(
>+            session_id=session.session_id,
>+            shadow_id=shadow_id),
>+        {"using": using, "value": value})
>+
>+
>+def test_null_parameter_value(session, http, get_shadow_page):
>+    session.url = get_shadow_page("<div><a href=# id=linkText>full link text</a></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+
>+    path = "/session/{session_id}/shadow/{shadow_id}/element".format(
>+        session_id=session.session_id, shadow_id=shadow_root.id)
>+    with http.post(path, None) as response:
>+        assert_error(Response.from_http(response), "invalid argument")
>+
>+
>+def test_no_top_browsing_context(session, closed_window):
>+    response = find_element(session, "notReal", "css selector", "foo")
>+    assert_error(response, "no such window")
>+
>+
>+def test_no_browsing_context(session, closed_frame):
>+    response = find_element(session, "notReal", "css selector", "foo")
>+    assert_error(response, "no such window")
>+
>+
>+@pytest.mark.parametrize("using", ["a", True, None, 1, [], {}])
>+def test_invalid_using_argument(session, using):
>+    # Step 1 - 2
>+    response = find_element(session, "notReal", using, "value")
>+    assert_error(response, "invalid argument")
>+
>+
>+@pytest.mark.parametrize("value", [None, [], {}])
>+def test_invalid_selector_argument(session, value):
>+    # Step 3 - 4
>+    response = find_element(session, "notReal", "css selector", value)
>+    assert_error(response, "invalid argument")
>+
>+
>+def test_detached_shadow_root(session, get_shadow_page):
>+    session.url = get_shadow_page("<div><input type='checkbox'/></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+    session.refresh()
>+
>+    response = find_element(session, shadow_root.id, "css", "input")
>+    assert_error(response, "detached shadow root")
>+
>+
>+def test_found_element_equivalence(session, get_shadow_page):
>+    session.url = get_shadow_page("<div><input type='checkbox'/></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    expected = session.execute_script("return arguments[0].shadowRoot.querySelector('input')",
>+                                      args=(custom_element,))
>+    shadow_root = custom_element.shadow_root
>+    response = find_element(session, shadow_root.id, "css", "input")
>+    value = assert_success(response)
>+    assert_same_element(session, value, expected)
>+
>+
>+@pytest.mark.parametrize("using,value",
>+                         [("css selector", "#linkText"),
>+                          ("link text", "full link text"),
>+                          ("partial link text", "link text"),
>+                          ("tag name", "a"),
>+                          ("xpath", "//a")])
>+def test_find_element(session, get_shadow_page, using, value):
>+    # Step 8 - 9
>+    session.url = get_shadow_page("<div><a href=# id=linkText>full link text</a></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    expected = session.execute_script("return arguments[0].shadowRoot.querySelector('#linkText')",
>+                                      args=(custom_element,))
>+    shadow_root = custom_element.shadow_root
>+    response = find_element(session, shadow_root.id, using, value)
>+    assert_success(response)
>+    assert_same_element(session, value, expected)
>+
>+
>+@pytest.mark.parametrize("document,value", [
>+    ("<a href=#>link text</a>", "link text"),
>+    ("<a href=#>&nbsp;link text&nbsp;</a>", "link text"),
>+    ("<a href=#>link<br>text</a>", "link\ntext"),
>+    ("<a href=#>link&amp;text</a>", "link&text"),
>+    ("<a href=#>LINK TEXT</a>", "LINK TEXT"),
>+    ("<a href=# style='text-transform: uppercase'>link text</a>", "LINK TEXT"),
>+])
>+def test_find_element_link_text(session, get_shadow_page, document, value):
>+    # Step 8 - 9
>+    session.url = get_shadow_page("<div>{0}</div>".format(document))
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    expected = session.execute_script("return arguments[0].shadowRoot.querySelectorAll('a')[0]",
>+                                      args=(custom_element,))
>+    shadow_root = custom_element.shadow_root
>+
>+    response = find_element(session, shadow_root.id, "link text", value)
>+    assert_success(response)
>+    assert_same_element(session, value, expected)
>+
>+
>+@pytest.mark.parametrize("document,value", [
>+    ("<a href=#>partial link text</a>", "link"),
>+    ("<a href=#>&nbsp;partial link text&nbsp;</a>", "link"),
>+    ("<a href=#>partial link text</a>", "k t"),
>+    ("<a href=#>partial link<br>text</a>", "k\nt"),
>+    ("<a href=#>partial link&amp;text</a>", "k&t"),
>+    ("<a href=#>PARTIAL LINK TEXT</a>", "LINK"),
>+    ("<a href=# style='text-transform: uppercase'>partial link text</a>", "LINK"),
>+])
>+def test_find_element_partial_link_text(session, get_shadow_page, document, value):
>+    # Step 8 - 9
>+    session.url = get_shadow_page("<div>{0}</div>".format(document))
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    expected = session.execute_script("return arguments[0].shadowRoot.querySelectorAll('a')[0]",
>+                                      args=(custom_element,))
>+    shadow_root = custom_element.shadow_root
>+
>+    response = find_element(session, shadow_root.id, "partial link text", value)
>+    assert_success(response)
>+    assert_same_element(session, value, expected)
>+
>+
>+@pytest.mark.parametrize("using,value", [("css selector", "#wontExist")])
>+def test_no_element(session, get_shadow_page, using, value):
>+    # Step 8 - 9
>+    session.url = get_shadow_page("<div></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+
>+    response = find_element(session, shadow_root.id, using, value)
>+    assert_error(response, "no such element")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_shadow_root/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_shadow_root/user_prompts.py
>new file mode 100644
>index 000000000000..3813a7df5d32
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_element_from_shadow_root/user_prompts.py
>@@ -0,0 +1,129 @@
>+# META: timeout=long
>+
>+import pytest
>+
>+from tests.support.asserts import (
>+    assert_error,
>+    assert_same_element,
>+    assert_success,
>+    assert_dialog_handled,
>+)
>+
>+
>+def find_element(session, shadow_id, using, value):
>+    return session.transport.send(
>+        "POST", "session/{session_id}/shadow/{shadow_id}/element".format(
>+            session_id=session.session_id,
>+            element_id=shadow_id),
>+        {"using": using, "value": value})
>+
>+
>+@pytest.fixture
>+def check_user_prompt_closed_without_exception(session, create_dialog, get_shadow_page):
>+    def check_user_prompt_closed_without_exception(dialog_type, retval):
>+        session.url = get_shadow_page("<div><p>bar</p><div>")
>+        outer_element = session.find.css("custom-shadow-element", all=False)
>+        shadow_root = outer_element.shadow_root
>+        inner_element = session.execute_script("return arguments[0].shadowRoot.querySelector('p')",
>+                                               args=(outer_element,))
>+
>+        create_dialog(dialog_type, text=dialog_type)
>+
>+        response = find_element(session, shadow_root.id, "css selector", "p")
>+        value = assert_success(response)
>+
>+        assert_dialog_handled(session, expected_text=dialog_type, expected_retval=retval)
>+
>+        assert_same_element(session, value, inner_element)
>+
>+    return check_user_prompt_closed_without_exception
>+
>+
>+@pytest.fixture
>+def check_user_prompt_closed_with_exception(session, create_dialog, get_shadow_page):
>+    def check_user_prompt_closed_with_exception(dialog_type, retval):
>+        session.url = get_shadow_page("<div><p>bar</p><div>")
>+        outer_element = session.find.css("custom-shadow-element", all=False)
>+        shadow_root = outer_element.shadow_root
>+
>+        create_dialog(dialog_type, text=dialog_type)
>+
>+        response = find_element(session, shadow_root.id, "css selector", "p")
>+        assert_error(response, "unexpected alert open")
>+
>+        assert_dialog_handled(session, expected_text=dialog_type, expected_retval=retval)
>+
>+    return check_user_prompt_closed_with_exception
>+
>+
>+@pytest.fixture
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, get_shadow_page):
>+    def check_user_prompt_not_closed_but_exception(dialog_type):
>+        session.url = get_shadow_page("<div><p>bar</p><div>")
>+        outer_element = session.find.css("custom-shadow-element", all=False)
>+        shadow_root = outer_element.shadow_root
>+
>+        create_dialog(dialog_type, text=dialog_type)
>+
>+        response = find_element(session, shadow_root.id, "css selector", "p")
>+        assert_error(response, "unexpected alert open")
>+
>+        assert session.alert.text == dialog_type
>+        session.alert.dismiss()
>+
>+    return check_user_prompt_not_closed_but_exception
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "accept"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", True),
>+    ("prompt", ""),
>+])
>+def test_accept(check_user_prompt_closed_without_exception, dialog_type, retval):
>+    check_user_prompt_closed_without_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "accept and notify"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", True),
>+    ("prompt", ""),
>+])
>+def test_accept_and_notify(check_user_prompt_closed_with_exception, dialog_type, retval):
>+    check_user_prompt_closed_with_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "dismiss"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", False),
>+    ("prompt", None),
>+])
>+def test_dismiss(check_user_prompt_closed_without_exception, dialog_type, retval):
>+    check_user_prompt_closed_without_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "dismiss and notify"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", False),
>+    ("prompt", None),
>+])
>+def test_dismiss_and_notify(check_user_prompt_closed_with_exception, dialog_type, retval):
>+    check_user_prompt_closed_with_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "ignore"})
>+@pytest.mark.parametrize("dialog_type", ["alert", "confirm", "prompt"])
>+def test_ignore(check_user_prompt_not_closed_but_exception, dialog_type):
>+    check_user_prompt_not_closed_but_exception(dialog_type)
>+
>+
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", False),
>+    ("prompt", None),
>+])
>+def test_default(check_user_prompt_closed_with_exception, dialog_type, retval):
>+    check_user_prompt_closed_with_exception(dialog_type, retval)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_elements/find.py b/WebDriverTests/imported/w3c/webdriver/tests/find_elements/find.py
>index c1381a0e82ac..47f009739385 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/find_elements/find.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_elements/find.py
>@@ -3,7 +3,6 @@ import pytest
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_same_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def find_elements(session, using, value):
>@@ -48,7 +47,7 @@ def test_invalid_selector_argument(session, value):
>                           ("partial link text", "link text"),
>                           ("tag name", "a"),
>                           ("xpath", "//a")])
>-def test_find_elements(session, using, value):
>+def test_find_elements(session, inline, using, value):
>     # Step 8 - 9
>     session.url = inline("<a href=# id=linkText>full link text</a>")
> 
>@@ -65,7 +64,7 @@ def test_find_elements(session, using, value):
>     ("<a href=#>LINK TEXT</a>", "LINK TEXT"),
>     ("<a href=# style='text-transform: uppercase'>link text</a>", "LINK TEXT"),
> ])
>-def test_find_elements_link_text(session, document, value):
>+def test_find_elements_link_text(session, inline, document, value):
>     # Step 8 - 9
>     session.url = inline("<a href=#>not wanted</a><br/>{0}".format(document))
>     expected = session.execute_script("return document.links[1];")
>@@ -88,7 +87,7 @@ def test_find_elements_link_text(session, document, value):
>     ("<a href=#>PARTIAL LINK TEXT</a>", "LINK"),
>     ("<a href=# style='text-transform: uppercase'>partial link text</a>", "LINK"),
> ])
>-def test_find_elements_partial_link_text(session, document, value):
>+def test_find_elements_partial_link_text(session, inline, document, value):
>     # Step 8 - 9
>     session.url = inline("<a href=#>not wanted</a><br/>{0}".format(document))
>     expected = session.execute_script("return document.links[1];")
>@@ -116,7 +115,7 @@ def test_no_element(session, using, value):
>                           ("partial link text", "link text"),
>                           ("tag name", "a"),
>                           ("xpath", "//*[name()='a']")])
>-def test_xhtml_namespace(session, using, value):
>+def test_xhtml_namespace(session, inline, using, value):
>     session.url = inline("""<a href="#" id="linkText">full link text</a>""",
>                          doctype="xhtml")
>     expected = session.execute_script("return document.links[0];")
>@@ -134,7 +133,7 @@ def test_xhtml_namespace(session, using, value):
>                          [("css selector", ":root"),
>                           ("tag name", "html"),
>                           ("xpath", "/html")])
>-def test_htmldocument(session, using, value):
>+def test_htmldocument(session, inline, using, value):
>     session.url = inline("")
>     response = find_elements(session, using, value)
>     value = assert_success(response)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_elements/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/find_elements/user_prompts.py
>index 01eb8ff3c863..f9a45e527515 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/find_elements/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_elements/user_prompts.py
>@@ -8,7 +8,6 @@ from tests.support.asserts import (
>     assert_success,
>     assert_dialog_handled,
> )
>-from tests.support.inline import inline
> 
> 
> def find_elements(session, using, value):
>@@ -18,7 +17,7 @@ def find_elements(session, using, value):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<p>bar</p>")
>         element = session.find.css("p", all=False)
>@@ -38,7 +37,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<p>bar</p>")
> 
>@@ -53,7 +52,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<p>bar</p>")
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_element/find.py b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_element/find.py
>index 5c267ba6479e..ae6f976e9f97 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_element/find.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_element/find.py
>@@ -3,7 +3,6 @@ import pytest
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_same_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def find_elements(session, element_id, using, value):
>@@ -14,7 +13,7 @@ def find_elements(session, element_id, using, value):
>         {"using": using, "value": value})
> 
> 
>-def test_null_parameter_value(session, http):
>+def test_null_parameter_value(session, http, inline):
>     session.url = inline("<div><a href=# id=linkText>full link text</a></div>")
>     element = session.find.css("div", all=False)
> 
>@@ -54,7 +53,7 @@ def test_invalid_selector_argument(session, value):
>                           ("partial link text", "link text"),
>                           ("tag name", "a"),
>                           ("xpath", "//a")])
>-def test_find_elements(session, using, value):
>+def test_find_elements(session, inline, using, value):
>     # Step 8 - 9
>     session.url = inline("<div><a href=# id=linkText>full link text</a></div>")
>     element = session.find.css("div", all=False)
>@@ -70,7 +69,7 @@ def test_find_elements(session, using, value):
>     ("<a href=#>LINK TEXT</a>", "LINK TEXT"),
>     ("<a href=# style='text-transform: uppercase'>link text</a>", "LINK TEXT"),
> ])
>-def test_find_elements_link_text(session, document, value):
>+def test_find_elements_link_text(session, inline, document, value):
>     # Step 8 - 9
>     session.url = inline("<div><a href=#>not wanted</a><br/>{0}</div>".format(document))
>     element = session.find.css("div", all=False)
>@@ -94,7 +93,7 @@ def test_find_elements_link_text(session, document, value):
>     ("<a href=#>PARTIAL LINK TEXT</a>", "LINK"),
>     ("<a href=# style='text-transform: uppercase'>partial link text</a>", "LINK"),
> ])
>-def test_find_elements_partial_link_text(session, document, value):
>+def test_find_elements_partial_link_text(session, inline, document, value):
>     # Step 8 - 9
>     session.url = inline("<div><a href=#>not wanted</a><br/>{0}</div>".format(document))
>     element = session.find.css("div", all=False)
>@@ -110,7 +109,7 @@ def test_find_elements_partial_link_text(session, document, value):
> 
> 
> @pytest.mark.parametrize("using,value", [("css selector", "#wontExist")])
>-def test_no_element(session, using, value):
>+def test_no_element(session, inline, using, value):
>     # Step 8 - 9
>     session.url = inline("<div></div>")
>     element = session.find.css("div", all=False)
>@@ -124,7 +123,7 @@ def test_no_element(session, using, value):
>                           ("partial link text", "link text"),
>                           ("tag name", "a"),
>                           ("xpath", "//*[name()='a']")])
>-def test_xhtml_namespace(session, using, value):
>+def test_xhtml_namespace(session, inline, using, value):
>     session.url = inline("""<p><a href="#" id="linkText">full link text</a></p>""",
>                          doctype="xhtml")
>     from_element = session.execute_script("""return document.querySelector("p")""")
>@@ -139,7 +138,7 @@ def test_xhtml_namespace(session, using, value):
>     assert_same_element(session, found_element, expected)
> 
> 
>-def test_parent_htmldocument(session):
>+def test_parent_htmldocument(session, inline):
>     session.url = inline("")
>     from_element = session.execute_script("""return document.querySelector("body")""")
>     expected = session.execute_script("return document.documentElement")
>@@ -153,7 +152,7 @@ def test_parent_htmldocument(session):
>     assert_same_element(session, found_element, expected)
> 
> 
>-def test_parent_of_document_node_errors(session):
>+def test_parent_of_document_node_errors(session, inline):
>     session.url = inline("")
>     from_element = session.execute_script("return document.documentElement")
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_element/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_element/user_prompts.py
>index ca7bc7735d08..467bec09a1bd 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_element/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_element/user_prompts.py
>@@ -8,7 +8,6 @@ from tests.support.asserts import (
>     assert_success,
>     assert_dialog_handled,
> )
>-from tests.support.inline import inline
> 
> 
> def find_elements(session, element_id, using, value):
>@@ -20,7 +19,7 @@ def find_elements(session, element_id, using, value):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<div><p>bar</p><div>")
>         outer_element = session.find.css("div", all=False)
>@@ -41,7 +40,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<div><p>bar</p><div>")
>         outer_element = session.find.css("div", all=False)
>@@ -57,7 +56,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<div><p>bar</p><div>")
>         outer_element = session.find.css("div", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_shadow_root/conftest.py b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_shadow_root/conftest.py
>new file mode 100644
>index 000000000000..b8fc93319f43
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_shadow_root/conftest.py
>@@ -0,0 +1,19 @@
>+import pytest
>+
>+@pytest.fixture
>+def get_shadow_page(inline):
>+    def get_shadow_page(shadow_content):
>+        return inline("""
>+            <custom-shadow-element></custom-shadow-element>
>+            <script>
>+                customElements.define('custom-shadow-element',
>+                    class extends HTMLElement {{
>+                        constructor() {{
>+                                super();
>+                                this.attachShadow({{mode: 'open'}}).innerHTML = `
>+                                    {{ {0} }}
>+                                `;
>+                            }}
>+                    }});
>+            </script>""".format(shadow_content))
>+    return get_shadow_page
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_shadow_root/find.py b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_shadow_root/find.py
>new file mode 100644
>index 000000000000..f70a4b45aadb
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_shadow_root/find.py
>@@ -0,0 +1,144 @@
>+import pytest
>+
>+from webdriver.transport import Response
>+
>+from tests.support.asserts import assert_error, assert_same_element, assert_success
>+
>+
>+def find_elements(session, shadow_id, using, value):
>+    return session.transport.send(
>+        "POST", "session/{session_id}/shadow/{shadow_id}/elements".format(
>+            session_id=session.session_id,
>+            shadow_id=shadow_id),
>+        {"using": using, "value": value})
>+
>+
>+def test_null_parameter_value(session, http, inline):
>+    session.url = inline("<div><a href=# id=linkText>full link text</a></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+
>+    path = "/session/{session_id}/shadow/{shadow_id}/elements".format(
>+        session_id=session.session_id, shadow_id=shadow_root.id)
>+    with http.post(path, None) as response:
>+        assert_error(Response.from_http(response), "invalid argument")
>+
>+
>+def test_no_top_browsing_context(session, closed_window):
>+    response = find_elements(session, "notReal", "css selector", "foo")
>+    assert_error(response, "no such window")
>+
>+
>+def test_no_browsing_context(session, closed_frame):
>+    response = find_elements(session, "notReal", "css selector", "foo")
>+    assert_error(response, "no such window")
>+
>+
>+@pytest.mark.parametrize("using", [("a"), (True), (None), (1), ([]), ({})])
>+def test_invalid_using_argument(session, using):
>+    # Step 1 - 2
>+    response = find_elements(session, "notReal", using, "value")
>+    assert_error(response, "invalid argument")
>+
>+
>+@pytest.mark.parametrize("value", [None, [], {}])
>+def test_invalid_selector_argument(session, value):
>+    # Step 3 - 4
>+    response = find_elements(session, "notReal", "css selector", value)
>+    assert_error(response, "invalid argument")
>+
>+
>+def test_detached_shadow_root(session, get_shadow_page):
>+    session.url = get_shadow_page("<div><input type='checkbox'/></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+    session.refresh()
>+
>+    response = find_elements(session, shadow_root.id, "css", "input")
>+    assert_error(response, "detached shadow root")
>+
>+
>+def test_find_elements_equivalence(session, get_shadow_page):
>+    session.url = get_shadow_page("<div><input id='check' type='checkbox'/><input id='text'/></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+    response = find_elements(session, shadow_root.id, "css", "input")
>+    assert_success(response)
>+
>+
>+@pytest.mark.parametrize("using,value",
>+                         [("css selector", "#linkText"),
>+                          ("link text", "full link text"),
>+                          ("partial link text", "link text"),
>+                          ("tag name", "a"),
>+                          ("xpath", "//a")])
>+def test_find_elements(session, get_shadow_page, using, value):
>+    # Step 8 - 9
>+    session.url = get_shadow_page("<div><a href=# id=linkText>full link text</a></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+    response = find_elements(session, shadow_root.id, using, value)
>+    assert_success(response)
>+
>+
>+@pytest.mark.parametrize("document,value", [
>+    ("<a href=#>link text</a>", "link text"),
>+    ("<a href=#>&nbsp;link text&nbsp;</a>", "link text"),
>+    ("<a href=#>link<br>text</a>", "link\ntext"),
>+    ("<a href=#>link&amp;text</a>", "link&text"),
>+    ("<a href=#>LINK TEXT</a>", "LINK TEXT"),
>+    ("<a href=# style='text-transform: uppercase'>link text</a>", "LINK TEXT"),
>+])
>+def test_find_elements_link_text(session, get_shadow_page, document, value):
>+    # Step 8 - 9
>+    session.url = get_shadow_page("<div><a href=#>not wanted</a><br/>{0}</div>".format(document))
>+    element = session.find.css("div", all=False)
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+    expected = session.execute_script("return arguments[0].shadowRoot.querySelectorAll('a')[1]",
>+                                      args=(custom_element,))
>+
>+    response = find_elements(session, shadow_root.id, "link text", value)
>+    value = assert_success(response)
>+    assert isinstance(value, list)
>+    assert len(value) == 1
>+
>+    found_element = value[0]
>+    assert_same_element(session, found_element, expected)
>+
>+
>+@pytest.mark.parametrize("document,value", [
>+    ("<a href=#>partial link text</a>", "link"),
>+    ("<a href=#>&nbsp;partial link text&nbsp;</a>", "link"),
>+    ("<a href=#>partial link text</a>", "k t"),
>+    ("<a href=#>partial link<br>text</a>", "k\nt"),
>+    ("<a href=#>partial link&amp;text</a>", "k&t"),
>+    ("<a href=#>PARTIAL LINK TEXT</a>", "LINK"),
>+    ("<a href=# style='text-transform: uppercase'>partial link text</a>", "LINK"),
>+])
>+def test_find_elements_partial_link_text(session, get_shadow_page, document, value):
>+    # Step 8 - 9
>+    session.url = get_shadow_page("<div><a href=#>not wanted</a><br/>{0}</div>".format(document))
>+    element = session.find.css("div", all=False)
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+    expected = session.execute_script("return arguments[0].shadowRoot.querySelectorAll('a')[1]",
>+                                      args=(custom_element,))
>+
>+    response = find_elements(session, shadow_root.id, "partial link text", value)
>+    value = assert_success(response)
>+    assert isinstance(value, list)
>+    assert len(value) == 1
>+
>+    found_element = value[0]
>+    assert_same_element(session, found_element, expected)
>+
>+
>+@pytest.mark.parametrize("using,value", [("css selector", "#wontExist")])
>+def test_no_element(session, get_shadow_page, using, value):
>+    # Step 8 - 9
>+    session.url = get_shadow_page("<div></div>")
>+    custom_element = session.find.css("custom-shadow-element", all=False)
>+    shadow_root = custom_element.shadow_root
>+    response = find_elements(session, shadow_root.id, using, value)
>+    assert response.body["value"] == []
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_shadow_root/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_shadow_root/user_prompts.py
>new file mode 100644
>index 000000000000..c4b903c836ef
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/find_elements_from_shadow_root/user_prompts.py
>@@ -0,0 +1,131 @@
>+# META: timeout=long
>+
>+import pytest
>+
>+from tests.support.asserts import (
>+    assert_error,
>+    assert_same_element,
>+    assert_success,
>+    assert_dialog_handled,
>+)
>+
>+
>+def find_elements(session, shadow_id, using, value):
>+    return session.transport.send(
>+        "POST", "session/{session_id}/shadow/{shadow_id}/elements".format(
>+            session_id=session.session_id,
>+            element_id=shadow_id),
>+        {"using": using, "value": value})
>+
>+
>+@pytest.fixture
>+def check_user_prompt_closed_without_exception(session, create_dialog, get_shadow_page):
>+    def check_user_prompt_closed_without_exception(dialog_type, retval):
>+        session.url = get_shadow_page("<div><p>bar</p><div>")
>+        outer_element = session.find.css("custom-shadow-element", all=False)
>+        shadow_root = outer_element.shadow_root
>+        inner_element = session.execute_script("return arguments[0].shadowRoot.querySelector('p')",
>+                                               args=(outer_element,))
>+
>+        create_dialog(dialog_type, text=dialog_type)
>+
>+        response = find_elements(session, shadow_root.id, "css selector", "p")
>+        value = assert_success(response)
>+        assert isinstance(value, list)
>+        assert len(value) == 1
>+
>+        assert_dialog_handled(session, expected_text=dialog_type, expected_retval=retval)
>+
>+        assert_same_element(session, value[0], inner_element)
>+
>+    return check_user_prompt_closed_without_exception
>+
>+
>+@pytest.fixture
>+def check_user_prompt_closed_with_exception(session, create_dialog, get_shadow_page):
>+    def check_user_prompt_closed_with_exception(dialog_type, retval):
>+        session.url = get_shadow_page("<div><p>bar</p><div>")
>+        outer_element = session.find.css("custom-shadow-element", all=False)
>+        shadow_root = outer_element.shadow_root
>+
>+        create_dialog(dialog_type, text=dialog_type)
>+
>+        response = find_elements(session, shadow_root.id, "css selector", "p")
>+        assert_error(response, "unexpected alert open")
>+
>+        assert_dialog_handled(session, expected_text=dialog_type, expected_retval=retval)
>+
>+    return check_user_prompt_closed_with_exception
>+
>+
>+@pytest.fixture
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, get_shadow_page):
>+    def check_user_prompt_not_closed_but_exception(dialog_type):
>+        session.url = get_shadow_page("<div><p>bar</p><div>")
>+        outer_element = session.find.css("custom-shadow-element", all=False)
>+        shadow_root = outer_element.shadow_root
>+
>+        create_dialog(dialog_type, text=dialog_type)
>+
>+        response = find_elements(session, shadow_root.id, "css selector", "p")
>+        assert_error(response, "unexpected alert open")
>+
>+        assert session.alert.text == dialog_type
>+        session.alert.dismiss()
>+
>+    return check_user_prompt_not_closed_but_exception
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "accept"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", True),
>+    ("prompt", ""),
>+])
>+def test_accept(check_user_prompt_closed_without_exception, dialog_type, retval):
>+    check_user_prompt_closed_without_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "accept and notify"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", True),
>+    ("prompt", ""),
>+])
>+def test_accept_and_notify(check_user_prompt_closed_with_exception, dialog_type, retval):
>+    check_user_prompt_closed_with_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "dismiss"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", False),
>+    ("prompt", None),
>+])
>+def test_dismiss(check_user_prompt_closed_without_exception, dialog_type, retval):
>+    check_user_prompt_closed_without_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "dismiss and notify"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", False),
>+    ("prompt", None),
>+])
>+def test_dismiss_and_notify(check_user_prompt_closed_with_exception, dialog_type, retval):
>+    check_user_prompt_closed_with_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "ignore"})
>+@pytest.mark.parametrize("dialog_type", ["alert", "confirm", "prompt"])
>+def test_ignore(check_user_prompt_not_closed_but_exception, dialog_type):
>+    check_user_prompt_not_closed_but_exception(dialog_type)
>+
>+
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", False),
>+    ("prompt", None),
>+])
>+def test_default(check_user_prompt_closed_with_exception, dialog_type, retval):
>+    check_user_prompt_closed_with_exception(dialog_type, retval)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/forward/forward.py b/WebDriverTests/imported/w3c/webdriver/tests/forward/forward.py
>index 4a1e21581518..97a935c8cd83 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/forward/forward.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/forward/forward.py
>@@ -1,5 +1,7 @@
>+import pytest
>+from webdriver import error
>+
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def forward(session):
>@@ -7,7 +9,7 @@ def forward(session):
>         "POST", "session/{session_id}/forward".format(**vars(session)))
> 
> 
>-def test_null_response_value(session):
>+def test_null_response_value(session, inline):
>     session.url = inline("<div>")
>     session.url = inline("<p>")
>     session.back()
>@@ -27,7 +29,7 @@ def test_no_browsing_context(session, closed_frame):
>     assert_success(response)
> 
> 
>-def test_no_browsing_history(session):
>+def test_no_browsing_history(session, inline):
>     url = inline("<div id=foo>")
> 
>     session.url = url
>@@ -40,7 +42,7 @@ def test_no_browsing_history(session):
>     assert element.property("id") == "foo"
> 
> 
>-def test_data_urls(session):
>+def test_data_urls(session, inline):
>     test_pages = [
>         inline("<p id=1>"),
>         inline("<p id=2>"),
>@@ -57,7 +59,7 @@ def test_data_urls(session):
>     assert session.url == test_pages[1]
> 
> 
>-def test_dismissed_beforeunload(session):
>+def test_dismissed_beforeunload(session, inline):
>     url_beforeunload = inline("""
>       <input type="text">
>       <script>
>@@ -105,7 +107,7 @@ def test_fragments(session, url):
>     assert session.url == test_pages[2]
> 
> 
>-def test_history_pushstate(session, url):
>+def test_history_pushstate(session, inline):
>     pushstate_page = inline("""
>       <script>
>         function pushState() {
>@@ -130,3 +132,45 @@ def test_history_pushstate(session, url):
> 
>     assert session.url == "{}#pushstate".format(pushstate_page)
>     assert session.execute_script("return history.state;") == {"foo": "bar"}
>+
>+
>+def test_removed_iframe(session, url, inline):
>+    page = inline("<p>foo")
>+
>+    session.url = url("/webdriver/tests/support/html/frames_no_bfcache.html")
>+    session.url = page
>+
>+    session.back()
>+
>+    subframe = session.find.css("#sub-frame", all=False)
>+    session.switch_frame(subframe)
>+
>+    response = forward(session)
>+    assert_success(response)
>+
>+    assert session.url == page
>+
>+
>+# Capability needed as long as no valid certificate is available:
>+#   https://github.com/web-platform-tests/wpt/issues/28847
>+@pytest.mark.capabilities({"acceptInsecureCerts": True})
>+def test_cross_origin(session, url):
>+    base_path = ("/webdriver/tests/support/html/subframe.html" +
>+                 "?pipe=header(Cross-Origin-Opener-Policy,same-origin")
>+    first_page = url(base_path, protocol="https")
>+    second_page = url(base_path, protocol="https", domain="alt")
>+
>+    session.url = first_page
>+    session.url = second_page
>+    session.back()
>+
>+    elem = session.find.css("#delete", all=False)
>+
>+    response = forward(session)
>+    assert_success(response)
>+
>+    assert session.url == second_page
>+
>+    with pytest.raises(error.StaleElementReferenceException):
>+        elem.click()
>+    elem = session.find.css("#delete", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/forward/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/forward/user_prompts.py
>index e5eea8f44571..3eeaf6e71cdb 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/forward/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/forward/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def forward(session):
>@@ -12,7 +11,7 @@ def forward(session):
> 
> 
> @pytest.fixture
>-def pages(session):
>+def pages(session, inline):
>     pages = [
>         inline("<p id=1>"),
>         inline("<p id=2>"),
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_active_element/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_active_element/get.py
>index 7f821f3a40d5..1085ad82f18f 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_active_element/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_active_element/get.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_error, assert_is_active_element, assert_success
>-from tests.support.inline import inline
> 
> 
> def read_global(session, name):
>@@ -21,7 +20,7 @@ def test_no_browsing_context(session, closed_frame):
>     assert_error(response, "no such window")
> 
> 
>-def test_success_document(session):
>+def test_success_document(session, inline):
>     session.url = inline("""
>         <body>
>             <h1>Heading</h1>
>@@ -36,7 +35,7 @@ def test_success_document(session):
>     assert_is_active_element(session, element)
> 
> 
>-def test_sucess_input(session):
>+def test_sucess_input(session, inline):
>     session.url = inline("""
>         <body>
>             <h1>Heading</h1>
>@@ -50,7 +49,7 @@ def test_sucess_input(session):
>     assert_is_active_element(session, element)
> 
> 
>-def test_sucess_input_non_interactable(session):
>+def test_sucess_input_non_interactable(session, inline):
>     session.url = inline("""
>         <body>
>             <h1>Heading</h1>
>@@ -64,7 +63,7 @@ def test_sucess_input_non_interactable(session):
>     assert_is_active_element(session, element)
> 
> 
>-def test_success_explicit_focus(session):
>+def test_success_explicit_focus(session, inline):
>     session.url = inline("""
>         <body>
>             <h1>Heading</h1>
>@@ -105,7 +104,7 @@ def test_success_explicit_focus(session):
>     assert_is_active_element(session, element)
> 
> 
>-def test_success_iframe_content(session):
>+def test_success_iframe_content(session, inline):
>     session.url = inline("<body></body>")
>     session.execute_script("""
>         let iframe = document.createElement('iframe');
>@@ -120,7 +119,7 @@ def test_success_iframe_content(session):
>     assert_is_active_element(session, element)
> 
> 
>-def test_missing_document_element(session):
>+def test_missing_document_element(session, inline):
>     session.url = inline("<body></body>")
>     session.execute_script("""
>         if (document.body.remove) {
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_active_element/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_active_element/user_prompts.py
>index 7fa7be1dde99..1ff77697b707 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_active_element/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_active_element/user_prompts.py
>@@ -8,7 +8,6 @@ from tests.support.asserts import (
>     assert_is_active_element,
>     assert_success
> )
>-from tests.support.inline import inline
> 
> 
> def get_active_element(session):
>@@ -17,7 +16,7 @@ def get_active_element(session):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input type=text>")
> 
>@@ -34,7 +33,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input type=text>")
> 
>@@ -49,7 +48,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input type=text>")
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_alert_text/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_alert_text/get.py
>index b64678653e08..7ee7ff1808f9 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_alert_text/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_alert_text/get.py
>@@ -1,9 +1,6 @@
>-from six import text_type
>-
> from webdriver.error import NoSuchAlertException
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> from tests.support.sync import Poll
> 
> 
>@@ -27,36 +24,36 @@ def test_no_user_prompt(session):
>     assert_error(response, "no such alert")
> 
> 
>-def test_get_alert_text(session):
>+def test_get_alert_text(session, inline):
>     session.url = inline("<script>window.alert('Hello');</script>")
>     response = get_alert_text(session)
>     assert_success(response)
>     assert isinstance(response.body, dict)
>     assert "value" in response.body
>     alert_text = response.body["value"]
>-    assert isinstance(alert_text, text_type)
>+    assert isinstance(alert_text, str)
>     assert alert_text == "Hello"
> 
> 
>-def test_get_confirm_text(session):
>+def test_get_confirm_text(session, inline):
>     session.url = inline("<script>window.confirm('Hello');</script>")
>     response = get_alert_text(session)
>     assert_success(response)
>     assert isinstance(response.body, dict)
>     assert "value" in response.body
>     confirm_text = response.body["value"]
>-    assert isinstance(confirm_text, text_type)
>+    assert isinstance(confirm_text, str)
>     assert confirm_text == "Hello"
> 
> 
>-def test_get_prompt_text(session):
>+def test_get_prompt_text(session, inline):
>     session.url = inline("<script>window.prompt('Enter Your Name: ', 'Federer');</script>")
>     response = get_alert_text(session)
>     assert_success(response)
>     assert isinstance(response.body, dict)
>     assert "value" in response.body
>     prompt_text = response.body["value"]
>-    assert isinstance(prompt_text, text_type)
>+    assert isinstance(prompt_text, str)
>     assert prompt_text == "Enter Your Name: "
> 
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_computed_label/__init__.py b/WebDriverTests/imported/w3c/webdriver/tests/get_computed_label/__init__.py
>new file mode 100644
>index 000000000000..e69de29bb2d1
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_computed_label/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_computed_label/get.py
>new file mode 100644
>index 000000000000..3904c6ce41f6
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_computed_label/get.py
>@@ -0,0 +1,36 @@
>+import pytest
>+
>+from webdriver.error import NoSuchAlertException
>+
>+from tests.support.asserts import assert_error, assert_success
>+from tests.support.inline import inline
>+
>+
>+def get_computed_label(session, element):
>+    return session.transport.send(
>+        "GET", "session/{session_id}/element/{element_id}/computedlabel".format(
>+            session_id=session.session_id,
>+            element_id=element))
>+
>+
>+def test_no_browsing_context(session, closed_window):
>+    response = get_computed_label(session)
>+    assert_error(response, "no such window")
>+
>+
>+def test_no_user_prompt(session):
>+    response = get_computed_label(session)
>+    assert_error(response, "no such alert")
>+
>+
>+@pytest.mark.parametrize("html,tag,label", [
>+    ("<button>ok</button>", "button", "ok"),
>+    ("<button aria-labelledby=\"one two\"></button><div id=one>ok</div><div id=two>go</div>", "button", "ok go"),
>+    ("<button aria-label=foo>bar</button>", "button", "foo"),
>+    ("<label><input> foo</label>", "input", "foo"),
>+    ("<label for=b>foo<label><input id=b>", "input", "foo")])
>+def test_get_computed_label(session, html, tag, label):
>+    session.url = inline("{0}".format(tag))
>+    element = session.find.css(tag, all=False)
>+    result = get_computed_label(session, element.id)
>+    assert_success(result, label)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_computed_role/__init__.py b/WebDriverTests/imported/w3c/webdriver/tests/get_computed_role/__init__.py
>new file mode 100644
>index 000000000000..e69de29bb2d1
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_computed_role/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_computed_role/get.py
>new file mode 100644
>index 000000000000..10fd628f156b
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_computed_role/get.py
>@@ -0,0 +1,34 @@
>+import pytest
>+
>+from webdriver.error import NoSuchAlertException
>+
>+from tests.support.asserts import assert_error, assert_success
>+from tests.support.inline import inline
>+
>+
>+def get_computed_role(session, element):
>+    return session.transport.send(
>+        "GET", "session/{session_id}/element/{element_id}/computedrole".format(
>+            session_id=session.session_id,
>+            element_id=element))
>+
>+
>+def test_no_browsing_context(session, closed_window):
>+    response = get_computed_role(session, "id")
>+    assert_error(response, "no such window")
>+
>+
>+def test_no_user_prompt(session):
>+    response = get_computed_role(session, "id")
>+    assert_error(response, "no such alert")
>+
>+
>+@pytest.mark.parametrize("html,tag,expected", [
>+    ("<li role=menuitem>foo", "li", "menu"),
>+    ("<input role=searchbox>", "input", "searchbox"),
>+    ("<img role=presentation>", "img", "presentation")])
>+def test_computed_roles(session, html, tag, expected):
>+    session.url = inline(html)
>+    element = session.find.css(tag, all=False)
>+    result = get_computed_role(session, element.id)
>+    assert_success(result, expected)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/get.py
>index 0383a8aba9e9..1ca13a1a6d5e 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/get.py
>@@ -1,11 +1,12 @@
>-from six import text_type
>+import pytest
> 
> from tests.support import platform_name
>-from tests.support.inline import inline
> from tests.support.asserts import assert_error, assert_success
> 
>-doc = inline("<p>frame")
>-alert_doc = inline("<script>window.alert()</script>")
>+
>+@pytest.fixture
>+def doc(inline):
>+    return inline("<p>frame")
> 
> 
> def get_current_url(session):
>@@ -18,14 +19,14 @@ def test_no_top_browsing_context(session, closed_window):
>     assert_error(response, "no such window")
> 
> 
>-def test_no_browsing_context(session, closed_frame):
>+def test_no_browsing_context(session, closed_frame, doc):
>     session.url = doc
> 
>     response = get_current_url(session)
>     assert_success(response, doc)
> 
> 
>-def test_get_current_url_matches_location(session):
>+def test_get_current_url_matches_location(session, doc):
>     session.url = doc
> 
>     response = get_current_url(session)
>@@ -37,7 +38,7 @@ def test_get_current_url_payload(session):
> 
>     response = get_current_url(session)
>     value = assert_success(response)
>-    assert isinstance(value, text_type)
>+    assert isinstance(value, str)
> 
> 
> def test_get_current_url_special_pages(session):
>@@ -76,7 +77,7 @@ def test_set_malformed_url(session):
>     assert_error(response, "invalid argument")
> 
> 
>-def test_get_current_url_after_modified_location(session):
>+def test_get_current_url_after_modified_location(session, doc):
>     session.url = doc
> 
>     response = get_current_url(session)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/iframe.py b/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/iframe.py
>index 944e61b583fd..80a960ce8a15 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/iframe.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/iframe.py
>@@ -1,7 +1,6 @@
> import pytest
> 
> from tests.support.asserts import assert_success
>-from tests.support.inline import iframe, inline
> 
> 
> """
>@@ -15,9 +14,20 @@ also enforce process isolation based on site origin.
> This is known to sometimes cause problems for WebDriver implementations.
> """
> 
>-frame_doc = inline("<p>frame")
>-one_frame_doc = inline("<iframe src='%s'></iframe>" % frame_doc)
>-nested_frames_doc = inline("<iframe src='%s'></iframe>" % one_frame_doc)
>+
>+@pytest.fixture
>+def frame_doc(inline):
>+    return inline("<p>frame")
>+
>+
>+@pytest.fixture
>+def one_frame_doc(inline, frame_doc):
>+    return inline("<iframe src='%s'></iframe>" % frame_doc)
>+
>+
>+@pytest.fixture
>+def nested_frames_doc(inline, one_frame_doc):
>+    return inline("<iframe src='%s'></iframe>" % one_frame_doc)
> 
> 
> def get_current_url(session):
>@@ -25,7 +35,7 @@ def get_current_url(session):
>         "GET", "session/{session_id}/url".format(**vars(session)))
> 
> 
>-def test_iframe(session):
>+def test_iframe(session, one_frame_doc):
>     top_level_doc = one_frame_doc
>     session.url = top_level_doc
> 
>@@ -37,7 +47,7 @@ def test_iframe(session):
>     assert_success(response, top_level_doc)
> 
> 
>-def test_nested_iframe(session):
>+def test_nested_iframe(session, nested_frames_doc):
>     session.url = nested_frames_doc
>     top_level_doc = session.url
> 
>@@ -53,7 +63,7 @@ def test_nested_iframe(session):
> 
> 
> @pytest.mark.parametrize("domain", ["", "alt"], ids=["same_origin", "cross_origin"])
>-def test_origin(session, domain, url):
>+def test_origin(session, inline, iframe, domain):
>     top_level_doc = inline(iframe("<p>frame", domain=domain))
> 
>     session.url = top_level_doc
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/user_prompts.py
>index f0e95d12f14e..d657c188241d 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_current_url/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def get_current_url(session):
>@@ -11,7 +10,7 @@ def get_current_url(session):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<p id=1>")
>         expected_url = session.url
>@@ -27,7 +26,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<p id=1>")
> 
>@@ -42,7 +41,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<p id=1>")
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_attribute/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_attribute/get.py
>index b18d9ca8b22a..528cbd29f020 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_attribute/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_attribute/get.py
>@@ -1,7 +1,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def get_element_attribute(session, element, attr):
>@@ -13,8 +12,14 @@ def get_element_attribute(session, element, attr):
> 
> 
> def test_no_top_browsing_context(session, closed_window):
>+    original_handle, element = closed_window
>+    response = get_element_attribute(session, element.id, "id")
>+    assert_error(response, "no such window")
>     response = get_element_attribute(session, "foo", "id")
>     assert_error(response, "no such window")
>+    session.window_handle = original_handle
>+    response = get_element_attribute(session, element.id, "id")
>+    assert_error(response, "no such element")
> 
> 
> def test_no_browsing_context(session, closed_frame):
>@@ -28,7 +33,7 @@ def test_element_not_found(session):
>     assert_error(result, "no such element")
> 
> 
>-def test_element_stale(session):
>+def test_element_stale(session, inline):
>     session.url = inline("<input id=foo>")
>     element = session.find.css("input", all=False)
>     session.refresh()
>@@ -36,7 +41,7 @@ def test_element_stale(session):
>     assert_error(result, "stale element reference")
> 
> 
>-def test_normal(session):
>+def test_normal(session, inline):
>     # 13.2 Step 5
>     session.url = inline("<input type=checkbox>")
>     element = session.find.css("input", all=False)
>@@ -73,7 +78,7 @@ def test_normal(session):
>     ("track", ["default"]),
>     ("video", ["autoplay", "controls", "loop", "muted"])
> ])
>-def test_boolean_attribute(session, tag, attrs):
>+def test_boolean_attribute(session, inline, tag, attrs):
>     for attr in attrs:
>         session.url = inline("<{0} {1}>".format(tag, attr))
>         element = session.find.css(tag, all=False)
>@@ -81,7 +86,7 @@ def test_boolean_attribute(session, tag, attrs):
>         assert_success(result, "true")
> 
> 
>-def test_global_boolean_attributes(session):
>+def test_global_boolean_attributes(session, inline):
>     session.url = inline("<p hidden>foo")
>     element = session.find.css("p", all=False)
>     result = get_element_attribute(session, element.id, "hidden")
>@@ -103,3 +108,14 @@ def test_global_boolean_attributes(session):
>     element = session.find.css("p", all=False)
>     result = get_element_attribute(session, element.id, "itemscope")
>     assert_success(result, None)
>+
>+
>+@pytest.mark.parametrize("is_relative", [True, False], ids=["relative", "absolute"])
>+def test_anchor_href(session, inline, url, is_relative):
>+    href = "/foo.html" if is_relative else url("/foo.html")
>+
>+    session.url = inline("<a href='{}'>foo</a>".format(href))
>+    element = session.find.css("a", all=False)
>+
>+    response = get_element_attribute(session, element.id, "href")
>+    assert_success(response, href)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_attribute/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_attribute/user_prompts.py
>index 5ee7929afdf8..009cb1e5fa1e 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_attribute/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_attribute/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success, assert_dialog_handled
>-from tests.support.inline import inline
> 
> 
> def get_element_attribute(session, element, attr):
>@@ -15,7 +14,7 @@ def get_element_attribute(session, element, attr):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input id=foo>")
>         element = session.find.css("#foo", all=False)
>@@ -31,7 +30,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input id=foo>")
>         element = session.find.css("#foo", all=False)
>@@ -47,7 +46,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input id=foo>")
>         element = session.find.css("#foo", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_css_value/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_css_value/get.py
>index 4e8704d50af9..369ca9c699f8 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_css_value/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_css_value/get.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def get_element_css_value(session, element_id, prop):
>@@ -14,9 +13,16 @@ def get_element_css_value(session, element_id, prop):
> 
> 
> def test_no_top_browsing_context(session, closed_window):
>+    original_handle, element = closed_window
>+    response = get_element_css_value(session, element.id, "display")
>+    assert_error(response, "no such window")
>     response = get_element_css_value(session, "foo", "bar")
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = get_element_css_value(session, element.id, "display")
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     response = get_element_css_value(session, "foo", "bar")
>@@ -28,7 +34,7 @@ def test_element_not_found(session):
>     assert_error(result, "no such element")
> 
> 
>-def test_element_stale(session):
>+def test_element_stale(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
>     session.refresh()
>@@ -37,7 +43,7 @@ def test_element_stale(session):
>     assert_error(result, "stale element reference")
> 
> 
>-def test_property_name_value(session):
>+def test_property_name_value(session, inline):
>     session.url = inline("""<input style="display: block">""")
>     element = session.find.css("input", all=False)
> 
>@@ -45,7 +51,7 @@ def test_property_name_value(session):
>     assert_success(result, "block")
> 
> 
>-def test_property_name_not_existent(session):
>+def test_property_name_not_existent(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_css_value/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_css_value/user_prompts.py
>index 529b6ae9183d..b1f9a3fb0a00 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_css_value/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_css_value/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success, assert_dialog_handled
>-from tests.support.inline import inline
> 
> 
> def get_element_css_value(session, element_id, prop):
>@@ -18,7 +17,7 @@ def get_element_css_value(session, element_id, prop):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("""<input style="display: block">""")
>         element = session.find.css("input", all=False)
>@@ -34,7 +33,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("""<input style="display: block">""")
>         element = session.find.css("input", all=False)
>@@ -50,7 +49,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("""<input style="display: block">""")
>         element = session.find.css("input", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_property/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_property/get.py
>index 5c0247edb702..10f7a08ae73e 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_property/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_property/get.py
>@@ -1,7 +1,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def get_element_property(session, element_id, prop):
>@@ -13,9 +12,16 @@ def get_element_property(session, element_id, prop):
> 
> 
> def test_no_top_browsing_context(session, closed_window):
>+    original_handle, element = closed_window
>+    response = get_element_property(session, element.id, "value")
>+    assert_error(response, "no such window")
>     response = get_element_property(session, "foo", "id")
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = get_element_property(session, element.id, "value")
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     response = get_element_property(session, "foo", "id")
>@@ -27,7 +33,7 @@ def test_element_not_found(session):
>     assert_error(response, "no such element")
> 
> 
>-def test_element_stale(session):
>+def test_element_stale(session, inline):
>     session.url = inline("<input id=foobar>")
>     element = session.find.css("input", all=False)
>     session.refresh()
>@@ -36,7 +42,7 @@ def test_element_stale(session):
>     assert_error(response, "stale element reference")
> 
> 
>-def test_property_non_existent(session):
>+def test_property_non_existent(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>@@ -45,7 +51,7 @@ def test_property_non_existent(session):
>     assert session.execute_script("return arguments[0].foo", args=(element,)) is None
> 
> 
>-def test_content_attribute(session):
>+def test_content_attribute(session, inline):
>     session.url = inline("<input value=foobar>")
>     element = session.find.css("input", all=False)
> 
>@@ -53,7 +59,7 @@ def test_content_attribute(session):
>     assert_success(response, "foobar")
> 
> 
>-def test_idl_attribute(session):
>+def test_idl_attribute(session, inline):
>     session.url = inline("<input value=foo>")
>     element = session.find.css("input", all=False)
>     session.execute_script("""arguments[0].value = "bar";""", args=(element,))
>@@ -70,7 +76,7 @@ def test_idl_attribute(session):
>     ("null", None),
>     ("undefined", None),
> ])
>-def test_primitives(session, js_primitive, py_primitive):
>+def test_primitives(session, inline, js_primitive, py_primitive):
>     session.url = inline("""
>         <input>
> 
>@@ -93,7 +99,7 @@ def test_primitives(session, js_primitive, py_primitive):
>     ("null", None),
>     ("undefined", None),
> ])
>-def test_primitives_set_by_execute_script(session, js_primitive, py_primitive):
>+def test_primitives_set_by_execute_script(session, inline, js_primitive, py_primitive):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
>     session.execute_script("arguments[0].foobar = {}".format(js_primitive), args=(element,))
>@@ -102,7 +108,7 @@ def test_primitives_set_by_execute_script(session, js_primitive, py_primitive):
>     assert_success(response, py_primitive)
> 
> 
>-def test_mutated_element(session):
>+def test_mutated_element(session, inline):
>     session.url = inline("<input type=checkbox>")
>     element = session.find.css("input", all=False)
>     element.click()
>@@ -114,3 +120,14 @@ def test_mutated_element(session):
> 
>     response = get_element_property(session, element.id, "checked")
>     assert_success(response, True)
>+
>+
>+@pytest.mark.parametrize("is_relative", [True, False], ids=["relative", "absolute"])
>+def test_anchor_href(session, inline, url, is_relative):
>+    href = "/foo.html" if is_relative else url("/foo.html")
>+
>+    session.url = inline("<a href='{}'>foo</a>".format(href))
>+    element = session.find.css("a", all=False)
>+
>+    response = get_element_property(session, element.id, "href")
>+    assert_success(response, url("/foo.html"))
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_property/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_property/user_prompts.py
>index 16a098536fde..e5e76947863e 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_property/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_property/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success, assert_dialog_handled
>-from tests.support.inline import inline
> 
> 
> def get_element_property(session, element_id, name):
>@@ -13,7 +12,7 @@ def get_element_property(session, element_id, name):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input id=foo>")
>         element = session.find.css("#foo", all=False)
>@@ -29,7 +28,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input id=foo>")
>         element = session.find.css("#foo", all=False)
>@@ -45,7 +44,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input id=foo>")
>         element = session.find.css("#foo", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_rect/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_rect/get.py
>index 494c45f8e45b..9ab4db4c604f 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_rect/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_rect/get.py
>@@ -1,6 +1,5 @@
> from tests.support.asserts import assert_error, assert_success
> from tests.support.helpers import element_rect
>-from tests.support.inline import inline
> 
> 
> def get_element_rect(session, element_id):
>@@ -14,9 +13,16 @@ def get_element_rect(session, element_id):
> 
> 
> def test_no_top_browsing_context(session, closed_window):
>+    original_handle, element = closed_window
>+    response = get_element_rect(session, element.id)
>+    assert_error(response, "no such window")
>     response = get_element_rect(session, "foo")
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = get_element_rect(session, element.id)
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     response = get_element_rect(session, "foo")
>@@ -28,7 +34,7 @@ def test_element_not_found(session):
>     assert_error(result, "no such element")
> 
> 
>-def test_element_stale(session):
>+def test_element_stale(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
>     session.refresh()
>@@ -37,7 +43,7 @@ def test_element_stale(session):
>     assert_error(result, "stale element reference")
> 
> 
>-def test_basic(session):
>+def test_basic(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_rect/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_rect/user_prompts.py
>index c51866cb8758..20131603381b 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_rect/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_rect/user_prompts.py
>@@ -4,7 +4,6 @@ import pytest
> 
> from tests.support.asserts import assert_error, assert_success, assert_dialog_handled
> from tests.support.helpers import element_rect
>-from tests.support.inline import inline
> 
> 
> def get_element_rect(session, element_id):
>@@ -18,7 +17,7 @@ def get_element_rect(session, element_id):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input>")
>         element = session.find.css("input", all=False)
>@@ -34,7 +33,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input>")
>         element = session.find.css("input", all=False)
>@@ -50,7 +49,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input>")
>         element = session.find.css("input", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_shadow_root/conftest.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_shadow_root/conftest.py
>new file mode 100644
>index 000000000000..afc0c91c3d3f
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_shadow_root/conftest.py
>@@ -0,0 +1,22 @@
>+import pytest
>+
>+@pytest.fixture
>+def checkbox_dom(inline):
>+    return inline("""
>+        <style>
>+            custom-checkbox-element {
>+                display:block; width:20px; height:20px;
>+            }
>+        </style>
>+        <custom-checkbox-element></custom-checkbox-element>
>+        <script>
>+            customElements.define('custom-checkbox-element',
>+                class extends HTMLElement {
>+                    constructor() {
>+                            super();
>+                            this.attachShadow({mode: 'open'}).innerHTML = `
>+                                <div><input type="checkbox"/></div>
>+                            `;
>+                        }
>+                });
>+        </script>""")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_shadow_root/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_shadow_root/get.py
>new file mode 100644
>index 000000000000..82e52420a2c0
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_shadow_root/get.py
>@@ -0,0 +1,60 @@
>+import pytest
>+
>+from tests.support.asserts import assert_error, assert_same_element, assert_success
>+
>+
>+def get_shadow_root(session, element_id):
>+    return session.transport.send(
>+        "GET", "session/{session_id}/element/{element_id}/shadow".format(
>+            session_id=session.session_id,
>+            element_id=element_id))
>+
>+
>+def test_no_top_browsing_context(session, closed_window):
>+    original_handle, element = closed_window
>+    response = get_shadow_root(session, element.id)
>+    assert_error(response, "no such window")
>+    response = get_shadow_root(session, "foo")
>+    assert_error(response, "no such window")
>+
>+    session.window_handle = original_handle
>+    response = get_shadow_root(session, element.id)
>+    assert_error(response, "no such element")
>+
>+
>+def test_no_browsing_context(session, closed_frame):
>+    response = get_shadow_root(session, "foo")
>+    assert_error(response, "no such window")
>+
>+
>+def test_element_not_found(session):
>+    result = get_shadow_root(session, "foo")
>+    assert_error(result, "no such element")
>+
>+
>+def test_element_stale(session, checkbox_dom):
>+    session.url = checkbox_dom
>+    element = session.find.css("custom-checkbox-element", all=False)
>+    session.refresh()
>+
>+    result = get_shadow_root(session, element.id)
>+    assert_error(result, "stale element reference")
>+
>+
>+def test_get_shadow_root(session, checkbox_dom):
>+    session.url = checkbox_dom
>+    expected = session.execute_script(
>+        "return document.querySelector('custom-checkbox-element').shadowRoot.host")
>+    custom_element = session.find.css("custom-checkbox-element", all=False)
>+    response = get_shadow_root(session, custom_element.id)
>+    value = assert_success(response)
>+    assert isinstance(value, dict)
>+    assert "shadow-6066-11e4-a52e-4f735466cecf" in value
>+    assert_same_element(session, custom_element, expected)
>+
>+
>+def test_no_shadow_root(session, inline):
>+    session.url = inline("<div><p>no shadow root</p></div>")
>+    element = session.find.css("div", all=False)
>+    response = get_shadow_root(session, element.id)
>+    assert_error(response, "no such shadow root")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_shadow_root/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_shadow_root/user_prompts.py
>new file mode 100644
>index 000000000000..32671b95a535
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_shadow_root/user_prompts.py
>@@ -0,0 +1,117 @@
>+# META: timeout=long
>+
>+import pytest
>+
>+from tests.support.asserts import assert_error, assert_success, assert_dialog_handled
>+
>+
>+def get_shadow_root(session, element_id):
>+    return session.transport.send(
>+        "GET", "session/{session_id}/element/{element_id}/shadow".format(
>+            session_id=session.session_id,
>+            element_id=element_id))
>+
>+
>+@pytest.fixture
>+def check_user_prompt_closed_without_exception(session, create_dialog, checkbox_dom):
>+    def check_user_prompt_closed_without_exception(dialog_type, retval):
>+        session.url = checkbox_dom
>+        element = session.find.css("custom-checkbox-element", all=False)
>+
>+        create_dialog(dialog_type, text=dialog_type)
>+
>+        response = get_shadow_root(session, element.id)
>+        value = assert_success(response)
>+        assert isinstance(value, dict)
>+
>+        assert_dialog_handled(session, expected_text=dialog_type, expected_retval=retval)
>+
>+    return check_user_prompt_closed_without_exception
>+
>+
>+@pytest.fixture
>+def check_user_prompt_closed_with_exception(session, create_dialog, checkbox_dom):
>+    def check_user_prompt_closed_with_exception(dialog_type, retval):
>+        session.url = checkbox_dom
>+        element = session.find.css("custom-checkbox-element", all=False)
>+
>+        create_dialog(dialog_type, text=dialog_type)
>+
>+        response = get_shadow_root(session, element.id)
>+        assert_error(response, "unexpected alert open")
>+
>+        assert_dialog_handled(session, expected_text=dialog_type, expected_retval=retval)
>+
>+    return check_user_prompt_closed_with_exception
>+
>+
>+@pytest.fixture
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, checkbox_dom):
>+    def check_user_prompt_not_closed_but_exception(dialog_type):
>+        session.url = checkbox_dom
>+        element = session.find.css("custom-checkbox-element", all=False)
>+
>+        create_dialog(dialog_type, text=dialog_type)
>+
>+        response = get_shadow_root(session, element.id)
>+        assert_error(response, "unexpected alert open")
>+
>+        assert session.alert.text == dialog_type
>+        session.alert.dismiss()
>+
>+    return check_user_prompt_not_closed_but_exception
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "accept"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", True),
>+    ("prompt", ""),
>+])
>+def test_accept(check_user_prompt_closed_without_exception, dialog_type, retval):
>+    check_user_prompt_closed_without_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "accept and notify"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", True),
>+    ("prompt", ""),
>+])
>+def test_accept_and_notify(check_user_prompt_closed_with_exception, dialog_type, retval):
>+    check_user_prompt_closed_with_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "dismiss"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", False),
>+    ("prompt", None),
>+])
>+def test_dismiss(check_user_prompt_closed_without_exception, dialog_type, retval):
>+    check_user_prompt_closed_without_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "dismiss and notify"})
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", False),
>+    ("prompt", None),
>+])
>+def test_dismiss_and_notify(check_user_prompt_closed_with_exception, dialog_type, retval):
>+    check_user_prompt_closed_with_exception(dialog_type, retval)
>+
>+
>+@pytest.mark.capabilities({"unhandledPromptBehavior": "ignore"})
>+@pytest.mark.parametrize("dialog_type", ["alert", "confirm", "prompt"])
>+def test_ignore(check_user_prompt_not_closed_but_exception, dialog_type):
>+    check_user_prompt_not_closed_but_exception(dialog_type)
>+
>+
>+@pytest.mark.parametrize("dialog_type, retval", [
>+    ("alert", None),
>+    ("confirm", False),
>+    ("prompt", None),
>+])
>+def test_default(check_user_prompt_closed_with_exception, dialog_type, retval):
>+    check_user_prompt_closed_with_exception(dialog_type, retval)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_tag_name/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_tag_name/get.py
>index ffe6dd641e82..cfc63bd788de 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_tag_name/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_tag_name/get.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def get_element_tag_name(session, element_id):
>@@ -10,9 +9,16 @@ def get_element_tag_name(session, element_id):
> 
> 
> def test_no_top_browsing_context(session, closed_window):
>+    original_handle, element = closed_window
>+    response = get_element_tag_name(session, element.id)
>+    assert_error(response, "no such window")
>     response = get_element_tag_name(session, "foo")
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = get_element_tag_name(session, element.id)
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     response = get_element_tag_name(session, "foo")
>@@ -24,7 +30,7 @@ def test_element_not_found(session):
>     assert_error(result, "no such element")
> 
> 
>-def test_element_stale(session):
>+def test_element_stale(session, inline):
>     session.url = inline("<input id=foo>")
>     element = session.find.css("input", all=False)
>     session.refresh()
>@@ -33,7 +39,7 @@ def test_element_stale(session):
>     assert_error(result, "stale element reference")
> 
> 
>-def test_get_element_tag_name(session):
>+def test_get_element_tag_name(session, inline):
>     session.url = inline("<input id=foo>")
>     element = session.find.css("input", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_tag_name/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_tag_name/user_prompts.py
>index 12a7d448421e..89697d0ad6a2 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_tag_name/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_tag_name/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success, assert_dialog_handled
>-from tests.support.inline import inline
> 
> 
> def get_element_tag_name(session, element_id):
>@@ -12,7 +11,7 @@ def get_element_tag_name(session, element_id):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input id=foo>")
>         element = session.find.css("#foo", all=False)
>@@ -28,7 +27,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input id=foo>")
>         element = session.find.css("#foo", all=False)
>@@ -44,7 +43,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input id=foo>")
>         element = session.find.css("#foo", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_text/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_text/get.py
>index 5f169a3a233b..72dc0cf735e5 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_text/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_text/get.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def get_element_text(session, element_id):
>@@ -10,29 +9,32 @@ def get_element_text(session, element_id):
> 
> 
> def test_no_top_browsing_context(session, closed_window):
>+    original_handle, element = closed_window
>+    response = get_element_text(session, element.id)
>+    assert_error(response, "no such window")
>     response = get_element_text(session, "foo")
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = get_element_text(session, element.id)
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     response = get_element_text(session, "foo")
>     assert_error(response, "no such window")
> 
> 
>-def test_getting_text_of_a_non_existant_element_is_an_error(session):
>+def test_getting_text_of_a_non_existant_element_is_an_error(session, inline):
>     session.url = inline("""<body>Hello world</body>""")
> 
>     result = get_element_text(session, "foo")
>     assert_error(result, "no such element")
> 
> 
>-def test_read_element_text(session):
>-    session.url = inline("""
>-        <body>
>-          Noise before <span id='id'>This has an ID</span>. Noise after
>-        </body>""")
>-
>+def test_read_element_text(session, inline):
>+    session.url = inline("Before f<span id='id'>oo</span> after")
>     element = session.find.css("#id", all=False)
> 
>     result = get_element_text(session, element.id)
>-    assert_success(result, "This has an ID")
>+    assert_success(result, "oo")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_element_text/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_element_text/user_prompts.py
>index 1ee5cde4da52..9f0bb386cdf5 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_element_text/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_element_text/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success, assert_dialog_handled
>-from tests.support.inline import inline
> 
> 
> def get_element_text(session, element_id):
>@@ -14,7 +13,7 @@ def get_element_text(session, element_id):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<p id=foo>bar</p>")
>         element = session.find.css("#foo", all=False)
>@@ -30,7 +29,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<p id=foo>bar</p>")
>         element = session.find.css("#foo", all=False)
>@@ -46,7 +45,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<p id=foo>bar</p>")
>         element = session.find.css("#foo", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_named_cookie/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_named_cookie/get.py
>index 102c18f0275c..d1e83b6a8152 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_named_cookie/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_named_cookie/get.py
>@@ -1,12 +1,10 @@
> import pytest
> 
> from datetime import datetime, timedelta
>-from six import integer_types, text_type
> 
> 
> from tests.support.asserts import assert_error, assert_success
> from tests.support.helpers import clear_all_cookies
>-from tests.support.inline import inline
> 
> 
> def get_named_cookie(session, name):
>@@ -38,13 +36,13 @@ def test_get_named_session_cookie(session, url):
>     # table for cookie conversion
>     # https://w3c.github.io/webdriver/#dfn-table-for-cookie-conversion
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
>     assert "path" in cookie
>-    assert isinstance(cookie["path"], text_type)
>+    assert isinstance(cookie["path"], str)
>     assert "domain" in cookie
>-    assert isinstance(cookie["domain"], text_type)
>+    assert isinstance(cookie["domain"], str)
>     assert "secure" in cookie
>     assert isinstance(cookie["secure"], bool)
>     assert "httpOnly" in cookie
>@@ -52,7 +50,7 @@ def test_get_named_session_cookie(session, url):
>     if "expiry" in cookie:
>         assert cookie.get("expiry") is None
>     assert "sameSite" in cookie
>-    assert isinstance(cookie["sameSite"], text_type)
>+    assert isinstance(cookie["sameSite"], str)
> 
>     assert cookie["name"] == "foo"
>     assert cookie["value"] == "bar"
>@@ -72,13 +70,13 @@ def test_get_named_cookie(session, url):
>     assert isinstance(cookie, dict)
> 
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
>     assert "expiry" in cookie
>-    assert isinstance(cookie["expiry"], integer_types)
>+    assert isinstance(cookie["expiry"], int)
>     assert "sameSite" in cookie
>-    assert isinstance(cookie["sameSite"], text_type)
>+    assert isinstance(cookie["sameSite"], str)
> 
>     assert cookie["name"] == "foo"
>     assert cookie["value"] == "bar"
>@@ -87,7 +85,7 @@ def test_get_named_cookie(session, url):
>         cookie["expiry"]).strftime(utc_string_format) == a_day_from_now
> 
> 
>-def test_duplicated_cookie(session, url, server_config):
>+def test_duplicated_cookie(session, url, server_config, inline):
>     new_cookie = {
>         "name": "hello",
>         "value": "world",
>@@ -113,11 +111,11 @@ def test_duplicated_cookie(session, url, server_config):
>     assert isinstance(cookie, dict)
> 
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
>     assert "sameSite" in cookie
>-    assert isinstance(cookie["sameSite"], text_type)
>+    assert isinstance(cookie["sameSite"], str)
> 
>     assert cookie["name"] == new_cookie["name"]
>     assert cookie["value"] == "newworld"
>@@ -136,11 +134,11 @@ def test_get_cookie_with_same_site_flag(session, url, same_site):
>     assert isinstance(cookie, dict)
> 
>     assert "name" in cookie
>-    assert isinstance(cookie["name"], text_type)
>+    assert isinstance(cookie["name"], str)
>     assert "value" in cookie
>-    assert isinstance(cookie["value"], text_type)
>+    assert isinstance(cookie["value"], str)
>     assert "sameSite" in cookie
>-    assert isinstance(cookie["sameSite"], text_type)
>+    assert isinstance(cookie["sameSite"], str)
> 
>     assert cookie["name"] == "foo"
>     assert cookie["value"] == "bar"
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_page_source/source.py b/WebDriverTests/imported/w3c/webdriver/tests/get_page_source/source.py
>index 5484ccbf2eef..cc4e208835c8 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_page_source/source.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_page_source/source.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def get_page_source(session):
>@@ -17,7 +16,7 @@ def test_no_browsing_context(session, closed_frame):
>     assert_error(response, "no such window")
> 
> 
>-def test_source_matches_outer_html(session):
>+def test_source_matches_outer_html(session, inline):
>     session.url = inline("<html><head><title>Cheese</title><body>Peas")
> 
>     expected = session.execute_script("return document.documentElement.outerHTML")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_page_source/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_page_source/user_prompts.py
>index 3b0cdff97dd9..13cb31595e61 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_page_source/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_page_source/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success, assert_dialog_handled
>-from tests.support.inline import inline
> 
> 
> def get_page_source(session):
>@@ -12,7 +11,7 @@ def get_page_source(session):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<div/>")
>         expected = session.execute_script("return document.documentElement.outerHTML")
>@@ -28,7 +27,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<div/>")
> 
>@@ -43,7 +42,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<div/>")
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_title/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_title/get.py
>index 34405774ba06..e696ec340339 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_title/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_title/get.py
>@@ -1,7 +1,4 @@
>-from six import text_type
>-
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def get_title(session):
>@@ -14,7 +11,7 @@ def test_payload(session):
> 
>     response = get_title(session)
>     value = assert_success(response)
>-    assert isinstance(value, text_type)
>+    assert isinstance(value, str)
> 
> 
> def test_no_top_browsing_context(session, closed_window):
>@@ -22,28 +19,28 @@ def test_no_top_browsing_context(session, closed_window):
>     assert_error(response, "no such window")
> 
> 
>-def test_no_browsing_context(session, closed_frame):
>+def test_no_browsing_context(session, closed_frame, inline):
>     session.url = inline("<title>Foo</title>")
> 
>     response = get_title(session)
>     assert_success(response, "Foo")
> 
> 
>-def test_with_duplicated_title(session):
>+def test_with_duplicated_title(session, inline):
>     session.url = inline("<title>First</title><title>Second</title>")
> 
>     result = get_title(session)
>     assert_success(result, "First")
> 
> 
>-def test_without_title(session):
>+def test_without_title(session, inline):
>     session.url = inline("<h2>Hello</h2>")
> 
>     result = get_title(session)
>     assert_success(result, "")
> 
> 
>-def test_after_modification(session):
>+def test_after_modification(session, inline):
>     session.url = inline("<title>Initial</title><h2>Hello</h2>")
>     session.execute_script("document.title = 'Updated'")
> 
>@@ -51,7 +48,7 @@ def test_after_modification(session):
>     assert_success(result, "Updated")
> 
> 
>-def test_strip_and_collapse(session):
>+def test_strip_and_collapse(session, inline):
>     document = "<title>   a b\tc\nd\t \n e\t\n </title><h2>Hello</h2>"
>     session.url = inline(document)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_title/iframe.py b/WebDriverTests/imported/w3c/webdriver/tests/get_title/iframe.py
>index 5991bf359069..9c5ab0b595d3 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_title/iframe.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_title/iframe.py
>@@ -1,7 +1,6 @@
> import pytest
> 
> from tests.support.asserts import assert_success
>-from tests.support.inline import iframe, inline
> 
> 
> """
>@@ -15,9 +14,20 @@ also enforce process isolation based on site origin.
> This is known to sometimes cause problems for WebDriver implementations.
> """
> 
>-frame_doc = inline("<title>cheese</title><p>frame")
>-one_frame_doc = inline("<title>bar</title><iframe src='%s'></iframe>" % frame_doc)
>-nested_frames_doc = inline("<title>foo</title><iframe src='%s'></iframe>" % one_frame_doc)
>+
>+@pytest.fixture
>+def frame_doc(inline):
>+    return inline("<title>cheese</title><p>frame")
>+
>+
>+@pytest.fixture
>+def one_frame_doc(inline, frame_doc):
>+    return inline("<title>bar</title><iframe src='%s'></iframe>" % frame_doc)
>+
>+
>+@pytest.fixture
>+def nested_frames_doc(inline, one_frame_doc):
>+    return inline("<title>foo</title><iframe src='%s'></iframe>" % one_frame_doc)
> 
> 
> def get_title(session):
>@@ -25,14 +35,14 @@ def get_title(session):
>         "GET", "session/{session_id}/title".format(**vars(session)))
> 
> 
>-def test_no_iframe(session):
>+def test_no_iframe(session, inline):
>     session.url = inline("<title>Foobar</title><h2>Hello</h2>")
> 
>     result = get_title(session)
>     assert_success(result, "Foobar")
> 
> 
>-def test_iframe(session):
>+def test_iframe(session, one_frame_doc):
>     session.url = one_frame_doc
> 
>     frame = session.find.css("iframe", all=False)
>@@ -43,7 +53,7 @@ def test_iframe(session):
>     assert_success(response, "bar")
> 
> 
>-def test_nested_iframe(session):
>+def test_nested_iframe(session, nested_frames_doc):
>     session.url = nested_frames_doc
> 
>     outer_frame = session.find.css("iframe", all=False)
>@@ -58,7 +68,7 @@ def test_nested_iframe(session):
> 
> 
> @pytest.mark.parametrize("domain", ["", "alt"], ids=["same_origin", "cross_origin"])
>-def test_origin(session, domain, url):
>+def test_origin(session, inline, iframe, domain):
>     session.url = inline("<title>foo</title>{}".format(
>         iframe("<title>bar</title><p>frame", domain=domain)))
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_title/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/get_title/user_prompts.py
>index 76d65c088a0b..0fd51e46f32a 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_title/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_title/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def get_title(session):
>@@ -12,7 +11,7 @@ def get_title(session):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<title>Foo</title>")
>         expected_title = session.title
>@@ -28,7 +27,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<title>Foo</title>")
> 
>@@ -43,7 +42,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<title>Foo</title>")
> 
>@@ -117,7 +116,7 @@ def test_default(check_user_prompt_closed_with_exception, dialog_type, retval):
> # trigger the creation of a dialog at all. Therefore, this test should only be
> # run in contexts that support the dialog (a condition that may not be
> # determined automatically).
>-# def test_title_with_non_simple_dialog(session):
>+# def test_title_with_non_simple_dialog(session, inline):
> #    document = "<title>With non-simple dialog</title><h2>Hello</h2>"
> #    spawn = """
> #        var done = arguments[0];
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_window_handle/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_window_handle/get.py
>index 8c262033c383..68441da5ef84 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_window_handle/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_window_handle/get.py
>@@ -1,3 +1,5 @@
>+import pytest
>+
> from tests.support.asserts import assert_error, assert_success
> 
> 
>@@ -19,3 +21,23 @@ def test_no_browsing_context(session, closed_frame):
> def test_basic(session):
>     response = get_window_handle(session)
>     assert_success(response, session.window_handle)
>+
>+
>+# Capability needed as long as no valid certificate is available:
>+#   https://github.com/web-platform-tests/wpt/issues/28847
>+@pytest.mark.capabilities({"acceptInsecureCerts": True})
>+def test_navigation_with_coop_headers(session, url):
>+    base_path = ("/webdriver/tests/support/html/subframe.html" +
>+                 "?pipe=header(Cross-Origin-Opener-Policy,same-origin")
>+
>+    session.url = url(base_path, protocol="https")
>+    response = get_window_handle(session)
>+    first_handle = assert_success(response)
>+
>+    # navigating to another domain with COOP headers will force a process change
>+    # in most browsers
>+    session.url = url(base_path, protocol="https", domain="alt")
>+    response = get_window_handle(session)
>+    second_handle = assert_success(response)
>+
>+    assert first_handle == second_handle
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/get_window_rect/get.py b/WebDriverTests/imported/w3c/webdriver/tests/get_window_rect/get.py
>index 793650feef46..f7592a30e067 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/get_window_rect/get.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/get_window_rect/get.py
>@@ -1,8 +1,4 @@
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
>-
>-
>-alert_doc = inline("<script>window.alert()</script>")
> 
> 
> def get_window_rect(session):
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/idlharness.html b/WebDriverTests/imported/w3c/webdriver/tests/idlharness.html
>deleted file mode 100644
>index d049d835f2fc..000000000000
>--- a/WebDriverTests/imported/w3c/webdriver/tests/idlharness.html
>+++ /dev/null
>@@ -1,23 +0,0 @@
>-<!doctype html>
>-<meta charset=utf-8>
>-<link rel="help" href="https://w3c.github.io/webdriver/">
>-<script src=/resources/testharness.js></script>
>-<script src=/resources/testharnessreport.js></script>
>-<script src=/resources/WebIDLParser.js></script>
>-<script src=/resources/idlharness.js></script>
>-
>-<script>
>-  "use strict";
>-
>-  promise_test(async () => {
>-    const idl_array = new IdlArray();
>-    const idl = await fetch("/interfaces/webdriver.idl").then(r => r.text());
>-    const html = await fetch("/interfaces/html.idl").then(r => r.text());
>-    idl_array.add_idls(idl);
>-    idl_array.add_dependency_idls(html);
>-    idl_array.add_objects({
>-      Navigator: ["navigator"]
>-    });
>-    idl_array.test();
>-  }, "Test IDL implementation of webdriver API");
>-</script>
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/idlharness.window.js b/WebDriverTests/imported/w3c/webdriver/tests/idlharness.window.js
>new file mode 100644
>index 000000000000..e92e151d8983
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/idlharness.window.js
>@@ -0,0 +1,16 @@
>+// META: script=/resources/WebIDLParser.js
>+// META: script=/resources/idlharness.js
>+
>+// https://w3c.github.io/webdriver/
>+
>+"use strict";
>+
>+idl_test(
>+  ["webdriver"],
>+  ["html"],
>+  idl_array => {
>+    idl_array.add_objects({
>+      Navigator: ["navigator"]
>+    });
>+  }
>+);
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/is_element_enabled/enabled.py b/WebDriverTests/imported/w3c/webdriver/tests/is_element_enabled/enabled.py
>index 88b1534ded1a..4a5a92ba5e91 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/is_element_enabled/enabled.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/is_element_enabled/enabled.py
>@@ -1,7 +1,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def is_element_enabled(session, element_id):
>@@ -15,16 +14,23 @@ def is_element_enabled(session, element_id):
> 
> 
> def test_no_top_browsing_context(session, closed_window):
>+    original_handle, element = closed_window
>+    response = is_element_enabled(session, element.id)
>+    assert_error(response, "no such window")
>     response = is_element_enabled(session, "foo")
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = is_element_enabled(session, element.id)
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     response = is_element_enabled(session, "foo")
>     assert_error(response, "no such window")
> 
> 
>-def test_element_stale(session):
>+def test_element_stale(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
>     session.refresh()
>@@ -34,7 +40,7 @@ def test_element_stale(session):
> 
> 
> @pytest.mark.parametrize("element", ["button", "input", "select", "textarea"])
>-def test_form_control_disabled(session, element):
>+def test_form_control_disabled(session, inline, element):
>     session.url = inline("<{} disabled/>".format(element))
>     element = session.find.css(element, all=False)
> 
>@@ -43,7 +49,7 @@ def test_form_control_disabled(session, element):
> 
> 
> @pytest.mark.parametrize("element", ["button", "input", "select", "textarea"])
>-def test_form_control_enabled(session, element):
>+def test_form_control_enabled(session, inline, element):
>     session.url = inline("<{}/>".format(element))
>     element = session.find.css(element, all=False)
> 
>@@ -52,7 +58,7 @@ def test_form_control_enabled(session, element):
> 
> 
> @pytest.mark.parametrize("element", ["button", "input", "select", "textarea"])
>-def test_fieldset_disabled_descendant(session, element):
>+def test_fieldset_disabled_descendant(session, inline, element):
>     session.url = inline("<fieldset disabled><{}/></fieldset>".format(element))
>     element = session.find.css(element, all=False)
> 
>@@ -61,7 +67,7 @@ def test_fieldset_disabled_descendant(session, element):
> 
> 
> @pytest.mark.parametrize("element", ["button", "input", "select", "textarea"])
>-def test_fieldset_enabled_descendant(session, element):
>+def test_fieldset_enabled_descendant(session, inline, element):
>     session.url = inline("<fieldset><{}/></fieldset>".format(element))
>     element = session.find.css(element, all=False)
> 
>@@ -70,7 +76,7 @@ def test_fieldset_enabled_descendant(session, element):
> 
> 
> @pytest.mark.parametrize("element", ["button", "input", "select", "textarea"])
>-def test_fieldset_disabled_descendant_legend(session, element):
>+def test_fieldset_disabled_descendant_legend(session, inline, element):
>     session.url = inline("<fieldset disabled><legend><{}/></legend></fieldset>".format(element))
>     element = session.find.css(element, all=False)
> 
>@@ -79,7 +85,7 @@ def test_fieldset_disabled_descendant_legend(session, element):
> 
> 
> @pytest.mark.parametrize("element", ["button", "input", "select", "textarea"])
>-def test_fieldset_enabled_descendant_legend(session, element):
>+def test_fieldset_enabled_descendant_legend(session, inline, element):
>     session.url = inline("<fieldset><legend><{}/></legend></fieldset>".format(element))
>     element = session.find.css(element, all=False)
> 
>@@ -88,7 +94,7 @@ def test_fieldset_enabled_descendant_legend(session, element):
> 
> 
> @pytest.mark.parametrize("element", ["button", "input", "select", "textarea"])
>-def test_xhtml_form_control_disabled(session, element):
>+def test_xhtml_form_control_disabled(session, inline, element):
>     session.url = inline("""<{} disabled="disabled"/>""".format(element),
>                          doctype="xhtml")
>     element = session.find.css(element, all=False)
>@@ -98,7 +104,7 @@ def test_xhtml_form_control_disabled(session, element):
> 
> 
> @pytest.mark.parametrize("element", ["button", "input", "select", "textarea"])
>-def test_xhtml_form_control_enabled(session, element):
>+def test_xhtml_form_control_enabled(session, inline, element):
>     session.url = inline("""<{}/>""".format(element), doctype="xhtml")
>     element = session.find.css(element, all=False)
> 
>@@ -106,7 +112,7 @@ def test_xhtml_form_control_enabled(session, element):
>     assert_success(result, True)
> 
> 
>-def test_xml_always_not_enabled(session):
>+def test_xml_always_not_enabled(session, inline):
>     session.url = inline("""<note></note>""", doctype="xml")
>     element = session.find.css("note", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/is_element_enabled/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/is_element_enabled/user_prompts.py
>index bd8bc81bdfcc..5dd7d582bd3d 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/is_element_enabled/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/is_element_enabled/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_dialog_handled, assert_success
>-from tests.support.inline import inline
> 
> 
> def is_element_enabled(session, element_id):
>@@ -17,7 +16,7 @@ def is_element_enabled(session, element_id):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input id=foo disabled>")
>         element = session.find.css("#foo", all=False)
>@@ -33,7 +32,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input id=foo disabled>")
>         element = session.find.css("#foo", all=False)
>@@ -49,7 +48,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input id=foo disabled>")
>         element = session.find.css("#foo", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/is_element_selected/selected.py b/WebDriverTests/imported/w3c/webdriver/tests/is_element_selected/selected.py
>index 79a1615dd9fd..6c8e8155cab1 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/is_element_selected/selected.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/is_element_selected/selected.py
>@@ -1,12 +1,18 @@
>+import pytest
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
>-check_doc = inline("""
>+@pytest.fixture
>+def check_doc(inline):
>+    return inline("""
>     <input id=checked type=checkbox checked>
>     <input id=notChecked type=checkbox>
>     """)
>-option_doc = inline("""
>+
>+
>+@pytest.fixture
>+def option_doc(inline):
>+    return inline("""
>     <select>
>       <option id=notSelected>r-
>       <option id=selected selected>r+
>@@ -22,16 +28,24 @@ def is_element_selected(session, element_id):
> 
> 
> def test_no_top_browsing_context(session, closed_window):
>+    original_handle, element = closed_window
>+
>+    response = is_element_selected(session, element.id)
>+    assert_error(response, "no such window")
>     response = is_element_selected(session, "foo")
>     assert_error(response, "no such window")
> 
>+    session.window_handle = original_handle
>+    response = is_element_selected(session, element.id)
>+    assert_error(response, "no such element")
>+
> 
> def test_no_browsing_context(session, closed_frame):
>     response = is_element_selected(session, "foo")
>     assert_error(response, "no such window")
> 
> 
>-def test_element_stale(session):
>+def test_element_stale(session, check_doc):
>     session.url = check_doc
>     element = session.find.css("#checked", all=False)
>     session.refresh()
>@@ -40,7 +54,7 @@ def test_element_stale(session):
>     assert_error(result, "stale element reference")
> 
> 
>-def test_element_checked(session):
>+def test_element_checked(session, check_doc):
>     session.url = check_doc
>     element = session.find.css("#checked", all=False)
> 
>@@ -48,7 +62,7 @@ def test_element_checked(session):
>     assert_success(result, True)
> 
> 
>-def test_checkbox_not_selected(session):
>+def test_checkbox_not_selected(session, check_doc):
>     session.url = check_doc
>     element = session.find.css("#notChecked", all=False)
> 
>@@ -56,7 +70,7 @@ def test_checkbox_not_selected(session):
>     assert_success(result, False)
> 
> 
>-def test_element_selected(session):
>+def test_element_selected(session, option_doc):
>     session.url = option_doc
>     element = session.find.css("#selected", all=False)
> 
>@@ -64,7 +78,7 @@ def test_element_selected(session):
>     assert_success(result, True)
> 
> 
>-def test_element_not_selected(session):
>+def test_element_not_selected(session, option_doc):
>     session.url = option_doc
>     element = session.find.css("#notSelected", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/is_element_selected/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/is_element_selected/user_prompts.py
>index 674f80c5c75b..96da2c08bd7e 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/is_element_selected/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/is_element_selected/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_dialog_handled, assert_success
>-from tests.support.inline import inline
> 
> 
> def is_element_selected(session, element_id):
>@@ -14,7 +13,7 @@ def is_element_selected(session, element_id):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input id=foo type=checkbox checked>")
>         element = session.find.css("#foo", all=False)
>@@ -31,7 +30,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input id=foo type=checkbox checked>")
>         element = session.find.css("#foo", all=False)
>@@ -47,7 +46,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input id=foo type=checkbox checked>")
>         element = session.find.css("#foo", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/maximize_window/maximize.py b/WebDriverTests/imported/w3c/webdriver/tests/maximize_window/maximize.py
>index 6903eece70d0..e233e45a10d7 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/maximize_window/maximize.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/maximize_window/maximize.py
>@@ -84,6 +84,7 @@ def test_maximize_when_resized_to_max_size(session):
>     session.end()
>     session.window.maximize()
>     available = session.window.size
>+    session.window.size = (800, 600)
>     session.end()
> 
>     session.window.size = available
>@@ -95,4 +96,5 @@ def test_maximize_when_resized_to_max_size(session):
>     # its expected dimensions.
>     before = session.window.size
>     session.window.maximize()
>-    assert session.window.size == before
>+    after = session.window.size
>+    assert after == before
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/navigate_to/navigate.py b/WebDriverTests/imported/w3c/webdriver/tests/navigate_to/navigate.py
>index 289e4321011f..25d768167aa0 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/navigate_to/navigate.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/navigate_to/navigate.py
>@@ -1,8 +1,11 @@
>-from tests.support import platform_name
>+import time
>+
>+import pytest
>+from webdriver import error
> from webdriver.transport import Response
> 
>+from tests.support import platform_name
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def navigate_to(session, url):
>@@ -17,7 +20,7 @@ def test_null_parameter_value(session, http):
>         assert_error(Response.from_http(response), "invalid argument")
> 
> 
>-def test_null_response_value(session):
>+def test_null_response_value(session, inline):
>     response = navigate_to(session, inline("<div/>"))
>     value = assert_success(response)
>     assert value is None
>@@ -28,7 +31,7 @@ def test_no_top_browsing_context(session, closed_window):
>     assert_error(response, "no such window")
> 
> 
>-def test_no_browsing_context(session, closed_frame):
>+def test_no_browsing_context(session, closed_frame, inline):
>     doc = inline("<p>foo")
> 
>     response = navigate_to(session, doc)
>@@ -52,3 +55,48 @@ def test_file_protocol(session, server_config):
>     if session.url.endswith('/'):
>         url += '/'
>     assert session.url == url
>+
>+
>+# Capability needed as long as no valid certificate is available:
>+#   https://github.com/web-platform-tests/wpt/issues/28847
>+@pytest.mark.capabilities({"acceptInsecureCerts": True})
>+def test_cross_origin(session, inline, url):
>+    base_path = ("/webdriver/tests/support/html/subframe.html" +
>+                 "?pipe=header(Cross-Origin-Opener-Policy,same-origin")
>+    first_page = url(base_path, protocol="https")
>+    second_page = url(base_path, protocol="https", domain="alt")
>+
>+    response = navigate_to(session, first_page)
>+    assert_success(response)
>+
>+    assert session.url == first_page
>+    elem = session.find.css("#delete", all=False)
>+
>+    response = navigate_to(session, second_page)
>+    assert_success(response)
>+
>+    assert session.url == second_page
>+    with pytest.raises(error.StaleElementReferenceException):
>+        elem.click()
>+
>+    session.find.css("#delete", all=False)
>+
>+
>+@pytest.mark.capabilities({"pageLoadStrategy": "eager"})
>+def test_utf8_meta_tag_after_1024_bytes(session, url):
>+    page = url("/webdriver/tests/support/html/meta-utf8-after-1024-bytes.html")
>+
>+    # Loading the page will cause a real parse commencing, and a renavigation
>+    # to the same URL getting triggered subsequently. Test that the navigate
>+    # command waits long enough.
>+    response = navigate_to(session, page)
>+    assert_success(response)
>+
>+    # If the command returns too early the property will be reset due to the
>+    # subsequent page load.
>+    session.execute_script("window.foo = 'bar'")
>+
>+    # Use delay to allow a possible missing subsequent navigation to start
>+    time.sleep(1)
>+
>+    assert session.execute_script("return window.foo") == "bar"
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/navigate_to/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/navigate_to/user_prompts.py
>index 6a94c11bf1d3..682bc40f4fe9 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/navigate_to/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/navigate_to/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_error, assert_success, assert_dialog_handled
>-from tests.support.inline import inline
> 
> 
> def navigate_to(session, url):
>@@ -13,7 +12,7 @@ def navigate_to(session, url):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         url = inline("<div/>")
> 
>@@ -30,7 +29,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         url = inline("<div/>")
> 
>@@ -47,7 +46,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         url = inline("<div/>")
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/new_session/response.py b/WebDriverTests/imported/w3c/webdriver/tests/new_session/response.py
>index cbe9e7d7fb14..43a8d5793114 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/new_session/response.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/new_session/response.py
>@@ -1,29 +1,27 @@
> import uuid
> import pytest
> 
>-from six import string_types
>-
> from tests.support.asserts import assert_success
> 
> 
> def test_sessionid(new_session, add_browser_capabilities):
>     response, _ = new_session({"capabilities": {"alwaysMatch": add_browser_capabilities({})}})
>     value = assert_success(response)
>-    assert isinstance(value["sessionId"], string_types)
>+    assert isinstance(value["sessionId"], str)
>     uuid.UUID(hex=value["sessionId"])
> 
> 
> @pytest.mark.parametrize("capability, type", [
>-    ("browserName", string_types),
>-    ("browserVersion", string_types),
>-    ("platformName", string_types),
>+    ("browserName", str),
>+    ("browserVersion", str),
>+    ("platformName", str),
>     ("acceptInsecureCerts", bool),
>-    ("pageLoadStrategy", string_types),
>+    ("pageLoadStrategy", str),
>     ("proxy", dict),
>     ("setWindowRect", bool),
>     ("timeouts", dict),
>     ("strictFileInteractability", bool),
>-    ("unhandledPromptBehavior", string_types),
>+    ("unhandledPromptBehavior", str),
> ])
> def test_capability_type(session, capability, type):
>     assert isinstance(session.capabilities, dict)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/new_session/websocket_url.py b/WebDriverTests/imported/w3c/webdriver/tests/new_session/websocket_url.py
>new file mode 100644
>index 000000000000..452decc90aa1
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/new_session/websocket_url.py
>@@ -0,0 +1,7 @@
>+from tests.support.asserts import assert_success
>+
>+def test_websocket_url(new_session, add_browser_capabilities):
>+    response, _ = new_session({"capabilities": {
>+        "alwaysMatch": add_browser_capabilities({"webSocketUrl": True})}})
>+    value = assert_success(response)
>+    assert value["capabilities"]["webSocketUrl"].startswith("ws://")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/new_window/new_tab.py b/WebDriverTests/imported/w3c/webdriver/tests/new_window/new_tab.py
>index 9300b04c45fa..270e4b51b88f 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/new_window/new_tab.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/new_window/new_tab.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_success
>-from tests.support.inline import inline
> 
> from . import opener, window_name
> 
>@@ -32,7 +31,7 @@ def test_keeps_current_window_handle(session):
>     assert session.window_handle == original_handle
> 
> 
>-def test_opens_about_blank_in_new_tab(session):
>+def test_opens_about_blank_in_new_tab(session, inline):
>     url = inline("<p>foo")
>     session.url = url
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/new_window/new_window.py b/WebDriverTests/imported/w3c/webdriver/tests/new_window/new_window.py
>index b34854cc2f3f..d3c224502704 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/new_window/new_window.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/new_window/new_window.py
>@@ -1,5 +1,4 @@
> from tests.support.asserts import assert_success
>-from tests.support.inline import inline
> 
> from . import opener, window_name
> 
>@@ -32,7 +31,7 @@ def test_keeps_current_window_handle(session):
>     assert session.window_handle == original_handle
> 
> 
>-def test_opens_about_blank_in_new_window(session):
>+def test_opens_about_blank_in_new_window(session, inline):
>     url = inline("<p>foo")
>     session.url = url
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/conftest.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/conftest.py
>index 970f7b7dd9be..188f8ddbb5ef 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/conftest.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/conftest.py
>@@ -32,6 +32,22 @@ def mouse_chain(session):
>         {"pointerType": "mouse"})
> 
> 
>+@pytest.fixture
>+def touch_chain(session):
>+    return session.actions.sequence(
>+        "pointer",
>+        "pointer_id",
>+        {"pointerType": "touch"})
>+
>+
>+@pytest.fixture
>+def pen_chain(session):
>+    return session.actions.sequence(
>+        "pointer",
>+        "pointer_id",
>+        {"pointerType": "pen"})
>+
>+
> @pytest.fixture
> def none_chain(session):
>     return session.actions.sequence("none", "none_id")
>@@ -66,3 +82,8 @@ def test_actions_page(session, url):
> @pytest.fixture
> def test_actions_scroll_page(session, url):
>     session.url = url("/webdriver/tests/perform_actions/support/test_actions_scroll_wdspec.html")
>+
>+
>+@pytest.fixture
>+def test_actions_pointer_page(session, url):
>+    session.url = url("/webdriver/tests/perform_actions/support/test_actions_pointer_wdspec.html")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/key_events.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/key_events.py
>index c3958015bfd4..8dbe024d1839 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/key_events.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/key_events.py
>@@ -5,7 +5,8 @@ from collections import defaultdict
> import pytest
> 
> from tests.perform_actions.support.keys import ALL_EVENTS, Keys, ALTERNATIVE_KEY_NAMES
>-from tests.perform_actions.support.refine import filter_dict, get_events, get_keys
>+from tests.perform_actions.support.refine import get_events, get_keys
>+from tests.support.helpers import filter_dict
> 
> 
> def test_keyup_only_sends_no_events(session, key_reporter, key_chain):
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer.py
>index ad546921460e..674d46d7b610 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer.py
>@@ -5,17 +5,12 @@ import pytest
> from webdriver.error import NoSuchWindowException
> 
> from tests.perform_actions.support.mouse import get_inview_center, get_viewport_rect
>-from tests.perform_actions.support.refine import filter_dict, get_events
>+from tests.perform_actions.support.refine import get_events
> from tests.support.asserts import assert_move_to_coordinates
>-from tests.support.inline import inline
>+from tests.support.helpers import filter_dict
> from tests.support.sync import Poll
> 
> 
>-def link_doc(dest):
>-    content = "<a href=\"{}\" id=\"link\">destination</a>".format(dest)
>-    return inline(content)
>-
>-
> def test_null_response_value(session, mouse_chain):
>     value = mouse_chain.click().perform()
>     assert value is None
>@@ -95,9 +90,9 @@ def test_click_element_center(session, test_actions_page, mouse_chain):
>             assert e["target"] == "outer"
> 
> 
>-def test_click_navigation(session, url):
>+def test_click_navigation(session, url, inline):
>     destination = url("/webdriver/tests/actions/support/test_actions_wdspec.html")
>-    start = link_doc(destination)
>+    start = inline("<a href=\"{}\" id=\"link\">destination</a>".format(destination))
> 
>     def click(link):
>         mouse_chain = session.actions.sequence(
>@@ -115,6 +110,85 @@ def test_click_navigation(session, url):
>     Poll(session, message=error_message).until(lambda s: s.url == destination)
> 
> 
>+def test_pen_pointer_properties(session, test_actions_pointer_page, pen_chain):
>+    pointerArea = session.find.css("#pointerArea", all=False)
>+    center = get_inview_center(pointerArea.rect, get_viewport_rect(session))
>+    pen_chain.pointer_move(0, 0, origin=pointerArea) \
>+        .pointer_down(pressure=0.36, tilt_x=-72, tilt_y=9, twist=86) \
>+        .pointer_move(10, 10, origin=pointerArea) \
>+        .pointer_up() \
>+        .pointer_move(80, 50, origin=pointerArea) \
>+        .perform()
>+    events = get_events(session)
>+    assert len(events) == 10
>+    event_types = [e["type"] for e in events]
>+    assert ["pointerover", "pointerenter", "pointermove", "pointerdown",
>+            "pointerover", "pointerenter", "pointermove", "pointerup",
>+            "pointerout", "pointerleave"] == event_types
>+    assert events[3]["type"] == "pointerdown"
>+    assert events[3]["pageX"] == pytest.approx(center["x"], abs=1.0)
>+    assert events[3]["pageY"] == pytest.approx(center["y"], abs=1.0)
>+    assert events[3]["target"] == "pointerArea"
>+    assert events[3]["pointerType"] == "pen"
>+    # The default value of width and height for mouse and pen inputs is 1
>+    assert round(events[3]["width"], 2) == 1
>+    assert round(events[3]["height"], 2) == 1
>+    assert round(events[3]["pressure"], 2) == 0.36
>+    assert events[3]["tiltX"] == -72
>+    assert events[3]["tiltY"] == 9
>+    assert events[3]["twist"] == 86
>+    assert events[6]["type"] == "pointermove"
>+    assert events[6]["pageX"] == pytest.approx(center["x"]+10, abs=1.0)
>+    assert events[6]["pageY"] == pytest.approx(center["y"]+10, abs=1.0)
>+    assert events[6]["target"] == "pointerArea"
>+    assert events[6]["pointerType"] == "pen"
>+    assert round(events[6]["width"], 2) == 1
>+    assert round(events[6]["height"], 2) == 1
>+    # The default value of pressure for all inputs is 0.5, other properties are 0
>+    assert round(events[6]["pressure"], 2) == 0.5
>+    assert events[6]["tiltX"] == 0
>+    assert events[6]["tiltY"] == 0
>+    assert events[6]["twist"] == 0
>+
>+
>+def test_touch_pointer_properties(session, test_actions_pointer_page, touch_chain):
>+    pointerArea = session.find.css("#pointerArea", all=False)
>+    center = get_inview_center(pointerArea.rect, get_viewport_rect(session))
>+    touch_chain.pointer_move(0, 0, origin=pointerArea) \
>+        .pointer_down(width=23, height=31, pressure=0.78, tilt_x=21, tilt_y=-8, twist=355) \
>+        .pointer_move(10, 10, origin=pointerArea, width=39, height=35, pressure=0.91, tilt_x=-19, tilt_y=62, twist=345) \
>+        .pointer_up() \
>+        .pointer_move(80, 50, origin=pointerArea) \
>+        .perform()
>+    events = get_events(session)
>+    assert len(events) == 7
>+    event_types = [e["type"] for e in events]
>+    assert ["pointerover", "pointerenter", "pointerdown", "pointermove",
>+            "pointerup", "pointerout", "pointerleave"] == event_types
>+    assert events[2]["type"] == "pointerdown"
>+    assert events[2]["pageX"] == pytest.approx(center["x"], abs=1.0)
>+    assert events[2]["pageY"] == pytest.approx(center["y"], abs=1.0)
>+    assert events[2]["target"] == "pointerArea"
>+    assert events[2]["pointerType"] == "touch"
>+    assert round(events[2]["width"], 2) == 23
>+    assert round(events[2]["height"], 2) == 31
>+    assert round(events[2]["pressure"], 2) == 0.78
>+    assert events[2]["tiltX"] == 21
>+    assert events[2]["tiltY"] == -8
>+    assert events[2]["twist"] == 355
>+    assert events[3]["type"] == "pointermove"
>+    assert events[3]["pageX"] == pytest.approx(center["x"]+10, abs=1.0)
>+    assert events[3]["pageY"] == pytest.approx(center["y"]+10, abs=1.0)
>+    assert events[3]["target"] == "pointerArea"
>+    assert events[3]["pointerType"] == "touch"
>+    assert round(events[3]["width"], 2) == 39
>+    assert round(events[3]["height"], 2) == 35
>+    assert round(events[3]["pressure"], 2) == 0.91
>+    assert events[3]["tiltX"] == -19
>+    assert events[3]["tiltY"] == 62
>+    assert events[3]["twist"] == 345
>+
>+
> @pytest.mark.parametrize("drag_duration", [0, 300, 800])
> @pytest.mark.parametrize("dx, dy", [
>     (20, 0), (0, 15), (10, 15), (-20, 0), (10, -15), (-10, -15)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_contextmenu.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_contextmenu.py
>index fda3f18bbc1c..50f684327f2a 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_contextmenu.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_contextmenu.py
>@@ -1,7 +1,8 @@
> import pytest
> 
> from tests.perform_actions.support.keys import Keys
>-from tests.perform_actions.support.refine import filter_dict, get_events
>+from tests.perform_actions.support.refine import get_events
>+from tests.support.helpers import filter_dict
> 
> 
> @pytest.mark.parametrize("modifier, prop", [
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_dblclick.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_dblclick.py
>index 8c89cef5f380..5be635a4d560 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_dblclick.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_dblclick.py
>@@ -1,7 +1,8 @@
> import pytest
> 
>-from tests.perform_actions.support.refine import filter_dict, get_events
>+from tests.perform_actions.support.refine import get_events
> from tests.support.asserts import assert_move_to_coordinates
>+from tests.support.helpers import filter_dict
> 
> 
> @pytest.mark.parametrize("click_pause", [0, 200])
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_modifier_click.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_modifier_click.py
>index ba81f6d090b2..28c4086e0f8c 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_modifier_click.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_modifier_click.py
>@@ -1,7 +1,8 @@
> import pytest
> 
> from tests.perform_actions.support.keys import Keys
>-from tests.perform_actions.support.refine import filter_dict, get_events
>+from tests.perform_actions.support.refine import get_events
>+from tests.support.helpers import filter_dict
> 
> 
> @pytest.mark.parametrize("modifier, prop", [
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_origin.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_origin.py
>index 4c9dc879e999..c4e5db7a0017 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_origin.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_origin.py
>@@ -3,23 +3,25 @@ import pytest
> from webdriver import MoveTargetOutOfBoundsException
> 
> from tests.perform_actions.support.mouse import get_inview_center, get_viewport_rect
>-from tests.support.inline import inline
> 
> 
>-def origin_doc(inner_style, outer_style=""):
>-    return inline("""
>-      <div id="outer" style="{1}"
>-           onmousemove="window.coords = {{x: event.clientX, y: event.clientY}}">
>-        <div id="inner" style="{0}"></div>
>-      </div>
>-    """.format(inner_style, outer_style))
>+@pytest.fixture
>+def origin_doc(inline):
>+    def origin_doc(inner_style, outer_style=""):
>+        return inline("""
>+          <div id="outer" style="{1}"
>+               onmousemove="window.coords = {{x: event.clientX, y: event.clientY}}">
>+            <div id="inner" style="{0}"></div>
>+          </div>
>+        """.format(inner_style, outer_style))
>+    return origin_doc
> 
> 
> def get_click_coordinates(session):
>     return session.execute_script("return window.coords;")
> 
> 
>-def test_viewport_inside(session, mouse_chain):
>+def test_viewport_inside(session, mouse_chain, origin_doc):
>     point = {"x": 50, "y": 50}
> 
>     session.url = origin_doc("width: 100px; height: 50px; background: green;")
>@@ -39,7 +41,7 @@ def test_viewport_outside(session, mouse_chain):
>             .perform()
> 
> 
>-def test_pointer_inside(session, mouse_chain):
>+def test_pointer_inside(session, mouse_chain, origin_doc):
>     start_point = {"x": 50, "y": 50}
>     offset = {"x": 10, "y": 5}
> 
>@@ -61,7 +63,7 @@ def test_pointer_outside(session, mouse_chain):
>             .perform()
> 
> 
>-def test_element_center_point(session, mouse_chain):
>+def test_element_center_point(session, mouse_chain, origin_doc):
>     session.url = origin_doc("width: 100px; height: 50px; background: green;")
>     elem = session.find.css("#inner", all=False)
>     center = get_inview_center(elem.rect, get_viewport_rect(session))
>@@ -75,7 +77,7 @@ def test_element_center_point(session, mouse_chain):
>     assert click_coords["y"] == pytest.approx(center["y"], abs = 1.0)
> 
> 
>-def test_element_center_point_with_offset(session, mouse_chain):
>+def test_element_center_point_with_offset(session, mouse_chain, origin_doc):
>     session.url = origin_doc("width: 100px; height: 50px; background: green;")
>     elem = session.find.css("#inner", all=False)
>     center = get_inview_center(elem.rect, get_viewport_rect(session))
>@@ -89,7 +91,7 @@ def test_element_center_point_with_offset(session, mouse_chain):
>     assert click_coords["y"] == pytest.approx(center["y"] + 15, abs = 1.0)
> 
> 
>-def test_element_in_view_center_point_partly_visible(session, mouse_chain):
>+def test_element_in_view_center_point_partly_visible(session, mouse_chain, origin_doc):
>     session.url = origin_doc("""width: 100px; height: 50px; background: green;
>                                 position: relative; left: -50px; top: -25px;""")
>     elem = session.find.css("#inner", all=False)
>@@ -104,7 +106,7 @@ def test_element_in_view_center_point_partly_visible(session, mouse_chain):
>     assert click_coords["y"] == pytest.approx(center["y"], abs = 1.0)
> 
> 
>-def test_element_larger_than_viewport(session, mouse_chain):
>+def test_element_larger_than_viewport(session, mouse_chain, origin_doc):
>     session.url = origin_doc("width: 300vw; height: 300vh; background: green;")
>     elem = session.find.css("#inner", all=False)
>     center = get_inview_center(elem.rect, get_viewport_rect(session))
>@@ -118,7 +120,7 @@ def test_element_larger_than_viewport(session, mouse_chain):
>     assert click_coords["y"] == pytest.approx(center["y"], abs = 1.0)
> 
> 
>-def test_element_outside_of_view_port(session, mouse_chain):
>+def test_element_outside_of_view_port(session, mouse_chain, origin_doc):
>     session.url = origin_doc("""width: 100px; height: 50px; background: green;
>                                 position: relative; left: -200px; top: -100px;""")
>     elem = session.find.css("#inner", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_pause_dblclick.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_pause_dblclick.py
>index 85679f3614a8..d46178a1d650 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_pause_dblclick.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_pause_dblclick.py
>@@ -1,5 +1,6 @@
> from tests.perform_actions.support.mouse import get_inview_center, get_viewport_rect
>-from tests.perform_actions.support.refine import filter_dict, get_events
>+from tests.perform_actions.support.refine import get_events
>+from tests.support.helpers import filter_dict
> 
> _DBLCLICK_INTERVAL = 640
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_tripleclick.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_tripleclick.py
>index 81d51be1a7e6..8239fc2a6062 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_tripleclick.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/pointer_tripleclick.py
>@@ -1,13 +1,13 @@
>-from tests.perform_actions.support.refine import filter_dict, get_events
>+from tests.perform_actions.support.refine import get_events
> from tests.support.asserts import assert_move_to_coordinates
>-from tests.support.inline import inline
>+from tests.support.helpers import filter_dict
> 
> lots_of_text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor "\
>                "incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud "\
>                "exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat."
> 
> 
>-def test_tripleclick_at_coordinates(session, mouse_chain):
>+def test_tripleclick_at_coordinates(session, mouse_chain, inline):
>     """
>         This test does a triple click on a coordinate. On desktop platforms
>         this will select a paragraph. On mobile this will not have the same
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/keys.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/keys.py
>index 2d38e1dff876..9e87ebfac1d7 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/keys.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/keys.py
>@@ -21,7 +21,6 @@ import sys
> 
> from collections import OrderedDict
> from inspect import getmembers
>-from six import text_type
> 
> class Keys(object):
>     """
>@@ -107,7 +106,7 @@ class Keys(object):
>     R_DELETE = u"\uE05D"
> 
> 
>-ALL_KEYS = getmembers(Keys, lambda x: type(x) == text_type)
>+ALL_KEYS = getmembers(Keys, lambda x: type(x) == str)
> 
> ALL_EVENTS = OrderedDict(
>     [
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/refine.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/refine.py
>index d5d24e934f61..35c962b9ecbf 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/refine.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/refine.py
>@@ -27,12 +27,3 @@ def get_keys(input_el):
>         return ""
>     else:
>         return rv
>-
>-
>-def filter_dict(source, d):
>-    """Filter `source` dict to only contain same keys as `d` dict.
>-
>-    :param source: dictionary to filter.
>-    :param d: dictionary whose keys determine the filtering.
>-    """
>-    return {k: source[k] for k in d.keys()}
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/test_actions_pointer_wdspec.html b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/test_actions_pointer_wdspec.html
>new file mode 100644
>index 000000000000..f1fd9b2da3f8
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/support/test_actions_pointer_wdspec.html
>@@ -0,0 +1,102 @@
>+ï»¿<!doctype html>
>+<meta charset=utf-8>
>+<html>
>+<head>
>+    <title>Test Actions</title>
>+    <style>
>+      div { padding:0px; margin: 0px; }
>+      #trackPointer { position: fixed; }
>+      #resultContainer { width: 600px; height: 60px; }
>+      .area { width: 100px; height: 50px; background-color: #ccc; }
>+    </style>
>+    <script>
>+        "use strict";
>+        var els = {};
>+        var allEvents = { events: [] };
>+        function displayMessage(message) {
>+            document.getElementById("events").innerHTML = "<p>" + message + "</p>";
>+        }
>+
>+        function appendMessage(message) {
>+            document.getElementById("events").innerHTML += "<p>" + message + "</p>";
>+        }
>+
>+        function recordPointerEvent(event) {
>+          if (event.type === "contextmenu") {
>+            event.preventDefault();
>+          }
>+          allEvents.events.push({
>+            "type": event.type,
>+            "button": event.button,
>+            "buttons": event.buttons,
>+            "pageX": event.pageX,
>+            "pageY": event.pageY,
>+            "ctrlKey": event.ctrlKey,
>+            "metaKey": event.metaKey,
>+            "altKey": event.altKey,
>+            "shiftKey": event.shiftKey,
>+            "target": event.target.id,
>+            "pointerType": event.pointerType,
>+            "width": event.width,
>+            "height": event.height,
>+            "pressure": event.pressure,
>+            "tangentialPressure": event.tangentialPressure,
>+            "tiltX": event.tiltX,
>+            "tiltY": event.tiltY,
>+            "twist": event.twist,
>+            "altitudeAngle": event.altitudeAngle,
>+            "azimuthAngle": event.azimuthAngle
>+          });
>+          appendMessage(event.type + " " +
>+              "button: " + event.button + ", " +
>+              "pageX: " + event.pageX + ", " +
>+              "pageY: " + event.pageY + ", " +
>+              "button: " + event.button + ", " +
>+              "buttons: " + event.buttons + ", " +
>+              "ctrlKey: " + event.ctrlKey + ", " +
>+              "altKey: " + event.altKey + ", " +
>+              "metaKey: " + event.metaKey + ", " +
>+              "shiftKey: " + event.shiftKey + ", " +
>+              "target id: " + event.target.id + ", " +
>+              "pointerType: " + event.pointerType + ", " +
>+              "width: " + event.width + ", " +
>+              "height: " + event.height + ", " +
>+              "pressure: " + event.pressure + ", " +
>+              "tangentialPressure: " + event.tangentialPressure + ", " +
>+              "tiltX: " + event.tiltX + ", " +
>+              "tiltY: " + event.tiltY + ", " +
>+              "twist: " + event.twist + ", " +
>+              "altitudeAngle: " + event.altitudeAngle + ", " +
>+              "azimuthAngle: " + event.azimuthAngle);
>+        }
>+
>+        function resetEvents() {
>+          allEvents.events.length = 0;
>+          displayMessage("");
>+        }
>+
>+        document.addEventListener("DOMContentLoaded", function() {
>+          var pointerArea = document.getElementById("pointerArea");
>+          pointerArea.addEventListener("pointerdown", recordPointerEvent);
>+          pointerArea.addEventListener("pointermove", recordPointerEvent);
>+          pointerArea.addEventListener("pointerup", recordPointerEvent);
>+          pointerArea.addEventListener("pointerover", recordPointerEvent);
>+          pointerArea.addEventListener("pointerenter", recordPointerEvent);
>+          pointerArea.addEventListener("pointerout", recordPointerEvent);
>+          pointerArea.addEventListener("pointerleave", recordPointerEvent);
>+        });
>+    </script>
>+</head>
>+<body>
>+  <div id="trackPointer" class="block"></div>
>+  <div>
>+    <h2>PointerReporter</h2>
>+    <div id="pointerArea" class="area">
>+    </div>
>+  </div>
>+  <div id="resultContainer">
>+    <h2>Events</h2>
>+    <div id="events"></div>
>+  </div>
>+</body>
>+</html>
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/wheel.py b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/wheel.py
>index fc84f2f2e014..67734800b19d 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/wheel.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/perform_actions/wheel.py
>@@ -2,8 +2,9 @@ import pytest
> 
> from webdriver.error import NoSuchWindowException
> 
>-from tests.perform_actions.support.refine import filter_dict, get_events
>+from tests.perform_actions.support.refine import get_events
> from tests.support.asserts import assert_move_to_coordinates
>+from tests.support.helpers import filter_dict
> 
> 
> def test_null_response_value(session, wheel_chain):
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/print/printcmd.py b/WebDriverTests/imported/w3c/webdriver/tests/print/printcmd.py
>index 341e069f7bb6..89296d2b146b 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/print/printcmd.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/print/printcmd.py
>@@ -1,11 +1,8 @@
>-import base64
>+from base64 import decodebytes
> 
> import pytest
> 
>-from six import ensure_binary
>-
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> 
> 
> def do_print(session, options):
>@@ -27,11 +24,11 @@ def test_no_top_browsing_context(session, closed_window):
> def test_no_browsing_context(session, closed_frame):
>     response = do_print(session, {})
>     value = assert_success(response)
>-    pdf = base64.decodestring(ensure_binary(value))
>+    pdf = decodebytes(value.encode())
>     assert_pdf(pdf)
> 
> 
>-def test_html_document(session):
>+def test_html_document(session, inline):
>     session.url = inline("Test")
> 
>     response = do_print(session, {
>@@ -40,7 +37,7 @@ def test_html_document(session):
>         "shrinkToFit": False
>     })
>     value = assert_success(response)
>-    pdf = base64.decodestring(ensure_binary(value))
>+    pdf = decodebytes(value.encode())
>     # TODO: Test that the output is reasonable
>     assert_pdf(pdf)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/print/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/print/user_prompts.py
>index a3f7a10ac372..0a29b518ac9a 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/print/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/print/user_prompts.py
>@@ -1,17 +1,14 @@
> # META: timeout=long
>-import base64
>+from base64 import decodebytes
> 
> import pytest
> 
>-from six import ensure_binary
>-
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_success
>-from tests.support.inline import inline
> from .printcmd import do_print, assert_pdf
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input/>")
> 
>@@ -20,7 +17,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
>         response = do_print(session, {})
>         value = assert_success(response)
> 
>-        pdf = base64.decodestring(ensure_binary(value))
>+        pdf = decodebytes(value.encode())
>         assert_dialog_handled(session, expected_text=dialog_type, expected_retval=retval)
> 
>         assert_pdf(pdf)
>@@ -29,7 +26,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input/>")
> 
>@@ -44,7 +41,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input/>")
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/refresh/refresh.py b/WebDriverTests/imported/w3c/webdriver/tests/refresh/refresh.py
>index eef413017e5e..33595d0ff71a 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/refresh/refresh.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/refresh/refresh.py
>@@ -2,7 +2,6 @@ import pytest
> 
> from webdriver.error import NoSuchElementException, StaleElementReferenceException
> 
>-from tests.support.inline import inline
> from tests.support.asserts import assert_error, assert_success
> 
> 
>@@ -11,7 +10,7 @@ def refresh(session):
>         "POST", "session/{session_id}/refresh".format(**vars(session)))
> 
> 
>-def test_null_response_value(session):
>+def test_null_response_value(session, inline):
>     session.url = inline("<div>")
> 
>     response = refresh(session)
>@@ -24,7 +23,7 @@ def test_no_top_browsing_context(session, closed_window):
>     assert_error(response, "no such window")
> 
> 
>-def test_no_browsing_context(session, closed_frame):
>+def test_no_browsing_context(session, closed_frame, inline):
>     url = inline("<div id=foo>")
> 
>     session.url = url
>@@ -40,7 +39,7 @@ def test_no_browsing_context(session, closed_frame):
>     assert session.find.css("#foo", all=False)
> 
> 
>-def test_basic(session):
>+def test_basic(session, inline):
>     url = inline("<div id=foo>")
> 
>     session.url = url
>@@ -56,7 +55,7 @@ def test_basic(session):
>     assert session.find.css("#foo", all=False)
> 
> 
>-def test_dismissed_beforeunload(session):
>+def test_dismissed_beforeunload(session, inline):
>     url_beforeunload = inline("""
>       <input type="text">
>       <script>
>@@ -79,7 +78,7 @@ def test_dismissed_beforeunload(session):
>     session.find.css("input", all=False)
> 
> 
>-def test_history_pushstate(session, url):
>+def test_history_pushstate(session, inline):
>     pushstate_page = inline("""
>       <script>
>         function pushState() {
>@@ -111,7 +110,7 @@ def test_history_pushstate(session, url):
>         element.property("id")
> 
> 
>-def test_refresh_switches_to_parent_browsing_context(session, create_frame):
>+def test_refresh_switches_to_parent_browsing_context(session, create_frame, inline):
>     session.url = inline("<div id=foo>")
> 
>     session.switch_frame(create_frame())
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/refresh/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/refresh/user_prompts.py
>index b8ef418e115f..7e944b53b096 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/refresh/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/refresh/user_prompts.py
>@@ -4,7 +4,6 @@ import pytest
> 
> from webdriver.error import StaleElementReferenceException
> 
>-from tests.support.inline import inline
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_success
> 
> 
>@@ -14,7 +13,7 @@ def refresh(session):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<div id=foo>")
>         element = session.find.css("#foo", all=False)
>@@ -33,7 +32,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<div id=foo>")
>         element = session.find.css("#foo", all=False)
>@@ -51,7 +50,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<div id=foo>")
>         element = session.find.css("#foo", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/release_actions/release.py b/WebDriverTests/imported/w3c/webdriver/tests/release_actions/release.py
>index 1f486f7759fd..5df1ff4be902 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/release_actions/release.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/release_actions/release.py
>@@ -20,4 +20,4 @@ def test_no_top_browsing_context(session, closed_window):
> 
> def test_no_browsing_context(session, closed_frame):
>     response = release_actions(session)
>-    assert_success(response)
>+    assert_error(response, "no such window")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/release_actions/sequence.py b/WebDriverTests/imported/w3c/webdriver/tests/release_actions/sequence.py
>index 2d816f8094b3..75143d85ca60 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/release_actions/sequence.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/release_actions/sequence.py
>@@ -1,6 +1,7 @@
> # META: timeout=long
> 
>-from tests.release_actions.support.refine import filter_dict, get_events, get_keys
>+from tests.release_actions.support.refine import get_events, get_keys
>+from tests.support.helpers import filter_dict
> 
> 
> def test_release_no_actions_sends_no_events(session, key_reporter):
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/release_actions/support/refine.py b/WebDriverTests/imported/w3c/webdriver/tests/release_actions/support/refine.py
>index 3a6d63e04ce9..90f722587c3b 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/release_actions/support/refine.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/release_actions/support/refine.py
>@@ -22,12 +22,3 @@ def get_keys(input_el):
>         return ""
>     else:
>         return rv
>-
>-
>-def filter_dict(source, d):
>-    """Filter `source` dict to only contain same keys as `d` dict.
>-
>-    :param source: dictionary to filter.
>-    :param d: dictionary whose keys determine the filtering.
>-    """
>-    return {k: source[k] for k in d.keys()}
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/send_alert_text/send.py b/WebDriverTests/imported/w3c/webdriver/tests/send_alert_text/send.py
>index 5da67590da34..d5846ad56b3b 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/send_alert_text/send.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/send_alert_text/send.py
>@@ -4,12 +4,11 @@ from webdriver.error import NoSuchAlertException
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline
> from tests.support.sync import Poll
> 
> 
> @pytest.fixture
>-def page(session):
>+def page(session, inline):
>     session.url = inline("""
>         <script>window.result = window.prompt('Enter Your Name: ', 'Name');</script>
>     """)
>@@ -55,7 +54,7 @@ def test_no_user_prompt(session):
> 
> 
> @pytest.mark.parametrize("dialog_type", ["alert", "confirm"])
>-def test_alert_element_not_interactable(session, dialog_type):
>+def test_alert_element_not_interactable(session, inline, dialog_type):
>     session.url = inline("<script>window.{}('Hello');</script>".format(dialog_type))
> 
>     response = send_alert_text(session, "Federer")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/status/status.py b/WebDriverTests/imported/w3c/webdriver/tests/status/status.py
>index 1f0f1bc4fe77..8c7ae22a67b5 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/status/status.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/status/status.py
>@@ -1,7 +1,5 @@
> import json
> 
>-from six import text_type
>-
> from tests.support.asserts import assert_success
> 
> 
>@@ -18,7 +16,7 @@ def test_get_status_no_session(http):
>         value = parsed_obj["value"]
> 
>         assert value["ready"] in [True, False]
>-        assert isinstance(value["message"], text_type)
>+        assert isinstance(value["message"], str)
> 
> 
> def test_status_with_session_running_on_endpoint_node(session):
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/asserts.py b/WebDriverTests/imported/w3c/webdriver/tests/support/asserts.py
>index 3c3d677c90ec..e60d53b6c6f0 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/support/asserts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/asserts.py
>@@ -1,8 +1,6 @@
>-import base64
> import imghdr
> import struct
>-
>-from six import ensure_binary, text_type
>+from base64 import decodebytes
> 
> from webdriver import Element, NoSuchAlertException, WebDriverException
> 
>@@ -52,8 +50,8 @@ def assert_error(response, error_code):
>     assert response.status == errors[error_code]
>     assert "value" in response.body
>     assert response.body["value"]["error"] == error_code
>-    assert isinstance(response.body["value"]["message"], text_type)
>-    assert isinstance(response.body["value"]["stacktrace"], text_type)
>+    assert isinstance(response.body["value"]["message"], str)
>+    assert isinstance(response.body["value"]["stacktrace"], str)
>     assert_response_headers(response.headers)
> 
> 
>@@ -214,6 +212,6 @@ def assert_move_to_coordinates(point, target, events):
> 
> def assert_png(screenshot):
>     """Test that screenshot is a Base64 encoded PNG file."""
>-    image = base64.decodestring(ensure_binary(screenshot))
>+    image = decodebytes(screenshot.encode())
>     mime_type = imghdr.what("", image)
>     assert mime_type == "png", "Expected image to be PNG, but it was {}".format(mime_type)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/authentication.py b/WebDriverTests/imported/w3c/webdriver/tests/support/authentication.py
>index 25a8eb95d114..9da4bb7be5ff 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/support/authentication.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/authentication.py
>@@ -1,15 +1,12 @@
>-from six.moves.urllib.parse import urlencode
>+from urllib.parse import urlencode
> 
> 
>-def basic_authentication(username=None, password=None, protocol="http"):
>-    from .fixtures import server_config, url
>-    build_url = url(server_config())
>-
>+def basic_authentication(url, username=None, password=None, protocol="http"):
>     query = {}
> 
>-    return build_url("/webdriver/tests/support/authentication.py",
>-                     query=urlencode(query),
>-                     protocol=protocol)
>+    return url("/webdriver/tests/support/authentication.py",
>+               query=urlencode(query),
>+               protocol=protocol)
> 
> 
> def main(request, response):
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/fixtures.py b/WebDriverTests/imported/w3c/webdriver/tests/support/fixtures.py
>index 957c4d05868b..db32931131d6 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/support/fixtures.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/fixtures.py
>@@ -2,15 +2,15 @@ import copy
> import json
> import os
> 
>+import asyncio
> import pytest
> import webdriver
> 
>-from six import string_types
>-
>-from six.moves.urllib.parse import urlunsplit
>+from urllib.parse import urlunsplit
> 
> from tests.support import defaults
>-from tests.support.helpers import cleanup_session
>+from tests.support.helpers import cleanup_session, deep_update
>+from tests.support.inline import build_inline
> from tests.support.http_request import HTTPRequest
> from tests.support.sync import Poll
> 
>@@ -38,6 +38,17 @@ def pytest_generate_tests(metafunc):
>             metafunc.parametrize("capabilities", marker.args, ids=None)
> 
> 
>+# Ensure that the event loop is restarted once per session rather than the default  of once per test
>+# if we don't do this, tests will try to reuse a closed event loop and fail with an error that the "future
>+# belongs to a different loop"
>+@pytest.fixture(scope="session")
>+def event_loop():
>+    """Change event_loop fixture to session level."""
>+    loop = asyncio.get_event_loop_policy().new_event_loop()
>+    yield loop
>+    loop.close()
>+
>+
> @pytest.fixture
> def add_event_listeners(session):
>     """Register listeners for tracked events on element."""
>@@ -94,7 +105,8 @@ def http(configuration):
> 
> @pytest.fixture
> def server_config():
>-    return json.loads(os.environ.get("WD_SERVER_CONFIG"))
>+    with open(os.environ.get("WD_SERVER_CONFIG_FILE"), "r") as f:
>+        return json.load(f)
> 
> 
> @pytest.fixture(scope="session")
>@@ -110,8 +122,23 @@ def configuration():
>     }
> 
> 
>+async def reset_current_session_if_necessary(caps, request_bidi):
>+    global _current_session
>+
>+    # If there is a session with different capabilities active or the current session
>+    # is of different type than the one we would like to create, end it now.
>+    if _current_session is not None:
>+        is_bidi = isinstance(_current_session, webdriver.BidiSession)
>+        if is_bidi != request_bidi or not _current_session.match(caps):
>+            if is_bidi:
>+                await _current_session.end()
>+            else:
>+                _current_session.end()
>+            _current_session = None
>+
>+
> @pytest.fixture(scope="function")
>-def session(capabilities, configuration, request):
>+async def session(capabilities, configuration, request):
>     """Create and start a session for a test that does not itself test session creation.
> 
>     By default the session will stay open after each test, but we always try to start a
>@@ -123,14 +150,10 @@ def session(capabilities, configuration, request):
>     # Update configuration capabilities with custom ones from the
>     # capabilities fixture, which can be set by tests
>     caps = copy.deepcopy(configuration["capabilities"])
>-    caps.update(capabilities)
>+    deep_update(caps, capabilities)
>     caps = {"alwaysMatch": caps}
> 
>-    # If there is a session with different capabilities active, end it now
>-    if _current_session is not None and (
>-            caps != _current_session.requested_capabilities):
>-        _current_session.end()
>-        _current_session = None
>+    await reset_current_session_if_necessary(caps, False)
> 
>     if _current_session is None:
>         _current_session = webdriver.Session(
>@@ -139,6 +162,7 @@ def session(capabilities, configuration, request):
>             capabilities=caps)
>     try:
>         _current_session.start()
>+
>     except webdriver.error.SessionNotCreatedException:
>         if not _current_session.session_id:
>             raise
>@@ -152,6 +176,48 @@ def session(capabilities, configuration, request):
>     cleanup_session(_current_session)
> 
> 
>+@pytest.fixture(scope="function")
>+async def bidi_session(capabilities, configuration, request):
>+    """Create and start a bidi session for a test that does not itself test
>+    bidi session creation.
>+    By default the session will stay open after each test, but we always try to start a
>+    new one and assume that if that fails there is already a valid session. This makes it
>+    possible to recover from some errors that might leave the session in a bad state, but
>+    does not demand that we start a new session per test."""
>+    global _current_session
>+
>+    # Update configuration capabilities with custom ones from the
>+    # capabilities fixture, which can be set by tests
>+    caps = copy.deepcopy(configuration["capabilities"])
>+    deep_update(caps, capabilities)
>+    caps = {"alwaysMatch": caps}
>+
>+    await reset_current_session_if_necessary(caps, True)
>+
>+    if _current_session is None:
>+        _current_session = webdriver.Session(
>+            configuration["host"],
>+            configuration["port"],
>+            capabilities=caps,
>+            enable_bidi=True)
>+
>+    try:
>+        _current_session.start()
>+        await _current_session.bidi_session.start()
>+    except webdriver.error.SessionNotCreatedException:
>+        if not _current_session.session_id:
>+            raise
>+
>+    # Enforce a fixed default window size and position
>+    _current_session.window.size = defaults.WINDOW_SIZE
>+    _current_session.window.position = defaults.WINDOW_POSITION
>+
>+    yield _current_session.bidi_session
>+
>+    await _current_session.bidi_session.end()
>+    cleanup_session(_current_session)
>+
>+
> @pytest.fixture(scope="function")
> def current_session():
>     return _current_session
>@@ -159,14 +225,13 @@ def current_session():
> 
> @pytest.fixture
> def url(server_config):
>-    def inner(path, protocol="http", domain="", subdomain="", query="", fragment=""):
>+    def url(path, protocol="http", domain="", subdomain="", query="", fragment=""):
>         domain = server_config["domains"][domain][subdomain]
>         port = server_config["ports"][protocol][0]
>         host = "{0}:{1}".format(domain, port)
>         return urlunsplit((protocol, host, path, query, fragment))
> 
>-    inner.__name__ = "url"
>-    return inner
>+    return url
> 
> 
> @pytest.fixture
>@@ -182,7 +247,7 @@ def create_dialog(session):
>         if text is None:
>             text = ""
> 
>-        assert isinstance(text, string_types), "`text` parameter must be a string"
>+        assert isinstance(text, str), "`text` parameter must be a string"
> 
>         # Script completes itself when the user prompt has been opened.
>         # For prompt() dialogs, add a value for the 'default' argument,
>@@ -238,15 +303,54 @@ def closed_frame(session, url):
> 
> 
> @pytest.fixture
>-def closed_window(session):
>+def closed_window(session, inline):
>     original_handle = session.window_handle
>     new_handle = session.new_window()
> 
>     session.window_handle = new_handle
>+    session.url = inline("<input id='a' value='b'>")
>+    element = session.find.css("input", all=False)
> 
>     session.window.close()
>     assert new_handle not in session.handles, "Unable to close window {}".format(new_handle)
> 
>-    yield new_handle
>+    yield (original_handle, element)
> 
>     session.window_handle = original_handle
>+
>+
>+@pytest.fixture
>+def inline(url):
>+    """Takes a source extract and produces well-formed documents.
>+
>+    Based on the desired document type, the extract is embedded with
>+    predefined boilerplate in order to produce well-formed documents.
>+    The media type and character set may also be individually configured.
>+
>+    This helper function originally used data URLs, but since these
>+    are not universally supported (or indeed standardised!) across
>+    browsers, it now delegates the serving of the document to wptserve.
>+    This file also acts as a wptserve handler (see the main function
>+    below) which configures the HTTP response using query parameters.
>+
>+    This function returns a URL to the wptserve handler, which in turn
>+    will serve an HTTP response with the requested source extract
>+    inlined in a well-formed document, and the Content-Type header
>+    optionally configured using the desired media type and character set.
>+
>+    Any additional keyword arguments are passed on to the build_url
>+    function, which comes from the url fixture.
>+    """
>+    def inline(src, **kwargs):
>+        return build_inline(url, src, **kwargs)
>+
>+    return inline
>+
>+
>+@pytest.fixture
>+def iframe(inline):
>+    """Inlines document extract as the source document of an <iframe>."""
>+    def iframe(src, **kwargs):
>+        return "<iframe src='{}'></iframe>".format(inline(src, **kwargs))
>+
>+    return iframe
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/helpers.py b/WebDriverTests/imported/w3c/webdriver/tests/support/helpers.py
>index f857083b4774..43bdb41cf983 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/support/helpers.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/helpers.py
>@@ -1,5 +1,6 @@
> from __future__ import print_function
> 
>+import collections
> import math
> import sys
> 
>@@ -106,6 +107,20 @@ def clear_all_cookies(session):
>     session.transport.send("DELETE", "session/%s/cookie" % session.session_id)
> 
> 
>+def deep_update(source, overrides):
>+    """
>+    Update a nested dictionary or similar mapping.
>+    Modify ``source`` in place.
>+    """
>+    for key, value in overrides.items():
>+        if isinstance(value, collections.Mapping) and value:
>+            returned = deep_update(source.get(key, {}), value)
>+            source[key] = returned
>+        else:
>+            source[key] = overrides[key]
>+    return source
>+
>+
> def document_dimensions(session):
>     return tuple(session.execute_script("""
>         let rect = document.documentElement.getBoundingClientRect();
>@@ -221,3 +236,27 @@ def available_screen_size(session):
>             screen.availHeight - screen.availTop,
>         ];
>         """))
>+
>+def filter_dict(source, d):
>+    """Filter `source` dict to only contain same keys as `d` dict.
>+
>+    :param source: dictionary to filter.
>+    :param d: dictionary whose keys determine the filtering.
>+    """
>+    return {k: source[k] for k in d.keys()}
>+
>+
>+def wait_for_new_handle(session, handles_before):
>+    def find_new_handle(session):
>+        new_handles = list(set(session.handles) - set(handles_before))
>+        if new_handles and len(new_handles) == 1:
>+            return new_handles[0]
>+        return None
>+
>+    wait = Poll(
>+        session,
>+        timeout=5,
>+        message="No new window has been opened")
>+
>+    return wait.until(find_new_handle)
>+
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/html/frames_no_bfcache.html b/WebDriverTests/imported/w3c/webdriver/tests/support/html/frames_no_bfcache.html
>new file mode 100644
>index 000000000000..1972187d21fe
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/html/frames_no_bfcache.html
>@@ -0,0 +1,18 @@
>+<html>
>+<head>
>+  <script type="text/javascript">
>+    function remove() {
>+      const frame = document.getElementById("sub-frame");
>+      const div = document.getElementById("delete");
>+      div.removeChild(frame);
>+    }
>+  </script>
>+</head>
>+
>+
>+<body onunload="">
>+  <div id="delete">
>+    <iframe src="subframe.html" id="sub-frame"></iframe>
>+  </div>
>+</body>
>+</html>
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/html/meta-utf8-after-1024-bytes.html b/WebDriverTests/imported/w3c/webdriver/tests/support/html/meta-utf8-after-1024-bytes.html
>new file mode 100644
>index 000000000000..b5916148b558
>--- /dev/null
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/html/meta-utf8-after-1024-bytes.html
>@@ -0,0 +1,17 @@
>+<!DOCTYPE html>
>+
>+<meta charset="utf-8">
>+<div id="body"></div>
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/http_request.py b/WebDriverTests/imported/w3c/webdriver/tests/support/http_request.py
>index 895d1319ac0a..242dc9c91887 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/support/http_request.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/http_request.py
>@@ -1,9 +1,7 @@
> import contextlib
> import json
> 
>-from six import text_type
>-
>-from six.moves.http_client import HTTPConnection
>+from http.client import HTTPConnection
> 
> 
> class HTTPRequest(object):
>@@ -31,7 +29,7 @@ class HTTPRequest(object):
>                 raise ValueError("Failed to encode request body as JSON: {}".format(
>                     json.dumps(body, indent=2)))
> 
>-            if isinstance(payload, text_type):
>+            if isinstance(payload, str):
>                 payload = body.encode("utf-8")
> 
>         conn = HTTPConnection(self.host, self.port)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/image.py b/WebDriverTests/imported/w3c/webdriver/tests/support/image.py
>index 6149ccccbe32..2e7ad8c1309b 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/support/image.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/image.py
>@@ -1,14 +1,12 @@
>-import base64
> import math
> import struct
>-
>-from six import ensure_binary
>+from base64 import decodebytes
> 
> from tests.support.asserts import assert_png
> 
> 
> def png_dimensions(screenshot):
>     assert_png(screenshot)
>-    image = base64.decodestring(ensure_binary(screenshot))
>+    image = decodebytes(screenshot.encode())
>     width, height = struct.unpack(">LL", image[16:24])
>     return int(width), int(height)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/inline.py b/WebDriverTests/imported/w3c/webdriver/tests/support/inline.py
>index d23ca75d1c80..494ca74f9265 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/support/inline.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/inline.py
>@@ -1,6 +1,6 @@
> """Helpers for inlining extracts of documents in tests."""
> 
>-from six.moves.urllib.parse import urlencode
>+from urllib.parse import urlencode
> 
> 
> BOILERPLATES = {
>@@ -24,31 +24,8 @@ MIME_TYPES = {
>     "xml": "text/xml",
> }
> 
>-def inline(src, doctype="html", mime=None, charset=None, **kwargs):
>-    """
>-    Takes a source extract and produces well-formed documents.
>-
>-    Based on the desired document type, the extract is embedded with
>-    predefined boilerplate in order to produce well-formed documents.
>-    The media type and character set may also be individually configured.
>-
>-    This helper function originally used data URLs, but since these
>-    are not universally supported (or indeed standardised!) across
>-    browsers, it now delegates the serving of the document to wptserve.
>-    This file also acts as a wptserve handler (see the main function
>-    below) which configures the HTTP response using query parameters.
>-
>-    This function returns a URL to the wptserve handler, which in turn
>-    will serve an HTTP response with the requested source extract
>-    inlined in a well-formed document, and the Content-Type header
>-    optionally configured using the desired media type and character set.
>-
>-    Any additional keyword arguments are passed on to the build_url
>-    function.
>-    """
>-    from .fixtures import server_config, url
>-    build_url = url(server_config())
> 
>+def build_inline(build_url, src, doctype="html", mime=None, charset=None, **kwargs):
>     if mime is None:
>         mime = MIME_TYPES[doctype]
>     if charset is None:
>@@ -62,11 +39,6 @@ def inline(src, doctype="html", mime=None, charset=None, **kwargs):
>         **kwargs)
> 
> 
>-def iframe(src, **kwargs):
>-    """Inlines document extract as the source document of an <iframe>."""
>-    return "<iframe src='{}'></iframe>".format(inline(src, **kwargs))
>-
>-
> def main(request, response):
>     doc = request.GET.first(b"doc", None)
>     mime = request.GET.first(b"mime", None)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/merge_dictionaries.py b/WebDriverTests/imported/w3c/webdriver/tests/support/merge_dictionaries.py
>index cf06c9b433ce..72f1cab352de 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/support/merge_dictionaries.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/merge_dictionaries.py
>@@ -1,10 +1,3 @@
>-def iteritems(d):
>-    """Create a key-value iterator for the given dict in both Python 2.x and
>-    Python 3.x environments"""
>-    if hasattr(d, "iteritems"):
>-        return d.iteritems()
>-    return d.items()
>-
> def merge_dictionaries(first, second):
>     """Given two dictionaries, create a third that defines all specified
>     key/value pairs. This merge_dictionaries is performed "deeply" on any nested
>@@ -12,7 +5,7 @@ def merge_dictionaries(first, second):
>     an exception will be raised."""
>     result = dict(first)
> 
>-    for key, value in iteritems(second):
>+    for key, value in second.items():
>         if key in result and result[key] != value:
>             if isinstance(result[key], dict) and isinstance(value, dict):
>                 result[key] = merge_dictionaries(result[key], value)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/support/sync.py b/WebDriverTests/imported/w3c/webdriver/tests/support/sync.py
>index fa5d18550cce..30ff872b6e15 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/support/sync.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/support/sync.py
>@@ -2,8 +2,6 @@ import collections
> import sys
> import time
> 
>-import six
>-
> from webdriver import error
> 
> 
>@@ -140,6 +138,6 @@ class Poll(object):
>             message = "Timed out after {} seconds".format(elapsed)
>             if self.exc_msg is not None:
>                 message = "{} with message: {}".format(message, self.exc_msg)
>-            six.reraise(self.exc_cls, self.exc_cls(message=message), tb)
>+            raise self.exc_cls(message=message).with_traceback(tb)
>         else:
>             return rv
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/cross_origin.py b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/cross_origin.py
>index 905f1eb56dce..633eba3f4248 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/cross_origin.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/cross_origin.py
>@@ -1,10 +1,9 @@
>-from six.moves.urllib.parse import urlparse
>+from urllib.parse import urlparse
> 
> import webdriver.protocol as protocol
> 
> from tests.support.asserts import assert_success
> from tests.support.helpers import document_location
>-from tests.support.inline import iframe, inline
> 
> 
> """
>@@ -27,7 +26,7 @@ def switch_to_frame(session, frame):
>         session=session)
> 
> 
>-def test_cross_origin_iframe(session, server_config):
>+def test_cross_origin_iframe(session, server_config, inline, iframe):
>     session.url = inline(iframe("", domain="alt"))
>     frame_element = session.find.css("iframe", all=False)
> 
>@@ -38,7 +37,7 @@ def test_cross_origin_iframe(session, server_config):
>     assert parse_result.netloc != server_config["browser_host"]
> 
> 
>-def test_nested_cross_origin_iframe(session, server_config):
>+def test_nested_cross_origin_iframe(session, server_config, inline, iframe):
>     frame2 = iframe("", domain="alt", subdomain="www")
>     frame1 = iframe(frame2)
>     top_doc = inline(frame1, domain="alt")
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch.py b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch.py
>index 705fa79a5de0..9ccab2c6c96d 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch.py
>@@ -2,11 +2,10 @@ import pytest
> 
> import webdriver.protocol as protocol
> 
>-from webdriver import StaleElementReferenceException
>+from webdriver import NoSuchElementException
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_same_element, assert_success
>-from tests.support.inline import inline, iframe
> 
> 
> def switch_to_frame(session, frame):
>@@ -17,18 +16,13 @@ def switch_to_frame(session, frame):
>         session=session)
> 
> 
>-def frameset(*docs):
>-    frames = list(map(lambda doc: "<frame src='{}'></frame>".format(inline(doc)), docs))
>-    return "<frameset rows='{}'>\n{}</frameset>".format(len(frames) * "*,", "\n".join(frames))
>-
>-
> def test_null_parameter_value(session, http):
>     path = "/session/{session_id}/frame".format(**vars(session))
>     with http.post(path, None) as response:
>         assert_error(Response.from_http(response), "invalid argument")
> 
> 
>-def test_null_response_value(session):
>+def test_null_response_value(session, inline, iframe):
>     session.url = inline(iframe("<p>foo"))
>     frame = session.find.css("iframe", all=False)
> 
>@@ -42,7 +36,16 @@ def test_null_response_value(session):
>     0,
>     {"element-6066-11e4-a52e-4f735466cecf": "foo"},
> ])
>-def test_no_top_browsing_context(session, closed_window, id):
>+def test_no_top_browsing_context(session, url, id):
>+    session.window_handle = session.new_window()
>+
>+    session.url = url("/webdriver/tests/support/html/frames.html")
>+
>+    subframe = session.find.css("#sub-frame", all=False)
>+    session.switch_frame(subframe)
>+
>+    session.window.close()
>+
>     response = switch_to_frame(session, id)
>     assert_error(response, "no such window")
> 
>@@ -61,13 +64,18 @@ def test_no_browsing_context(session, closed_frame, id):
>         assert_error(response, "no such window")
> 
> 
>+def test_no_browsing_context_when_already_top_level(session, closed_window):
>+    response = switch_to_frame(session, None)
>+    assert_error(response, "no such window")
>+
>+
> @pytest.mark.parametrize("value", ["foo", True, [], {}])
> def test_frame_id_invalid_types(session, value):
>     response = switch_to_frame(session, value)
>     assert_error(response, "invalid argument")
> 
> 
>-def test_frame_id_null(session):
>+def test_frame_id_null(session, inline, iframe):
>     session.url = inline(iframe("{}<div>foo".format(iframe("<p>bar"))))
> 
>     frame1 = session.find.css("iframe", all=False)
>@@ -82,10 +90,27 @@ def test_frame_id_null(session):
>     response = switch_to_frame(session, None)
>     assert_success(response)
> 
>-    with pytest.raises(StaleElementReferenceException):
>+    with pytest.raises(NoSuchElementException):
>         element2.text
>-    with pytest.raises(StaleElementReferenceException):
>+    with pytest.raises(NoSuchElementException):
>         element1.text
> 
>     frame = session.find.css("iframe", all=False)
>     assert_same_element(session, frame, frame1)
>+
>+
>+def test_find_element_while_frame_is_still_loading(session, url):
>+    session.timeouts.implicit = 5
>+
>+    frame_url = url("/webdriver/tests/support/html/subframe.html?pipe=trickle(d2)")
>+    page_url = "<html><body><iframe src='{}'></iframe></body></html>".format(frame_url)
>+
>+    session.execute_script(
>+        "document.documentElement.innerHTML = arguments[0];", args=[page_url])
>+
>+    frame1 = session.find.css("iframe", all=False)
>+    session.switch_frame(frame1)
>+
>+    # Ensure that the is always a valid browsing context, and the element
>+    # can be found eventually.
>+    session.find.css("#delete", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch_number.py b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch_number.py
>index 77529544679a..c8858e77ff10 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch_number.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch_number.py
>@@ -3,7 +3,6 @@ import pytest
> import webdriver.protocol as protocol
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline, iframe
> 
> 
> def switch_to_frame(session, frame):
>@@ -21,7 +20,7 @@ def test_frame_id_number_out_of_bounds(session, value):
> 
> 
> @pytest.mark.parametrize("index", [1, 65535])
>-def test_frame_id_number_index_out_of_bounds(session, index):
>+def test_frame_id_number_index_out_of_bounds(session, inline, iframe, index):
>     session.url = inline(iframe("<p>foo"))
> 
>     response = switch_to_frame(session, index)
>@@ -29,7 +28,7 @@ def test_frame_id_number_index_out_of_bounds(session, index):
> 
> 
> @pytest.mark.parametrize("index, value", [[0, "foo"], [1, "bar"]])
>-def test_frame_id_number_index(session, index, value):
>+def test_frame_id_number_index(session, inline, iframe, index, value):
>     session.url = inline("{}{}".format(iframe("<p>foo"), iframe("<p>bar")))
> 
>     response = switch_to_frame(session, index)
>@@ -39,7 +38,7 @@ def test_frame_id_number_index(session, index, value):
>     assert element.text == value
> 
> 
>-def test_frame_id_number_index_nested(session):
>+def test_frame_id_number_index_nested(session, inline, iframe):
>     session.url = inline(iframe("{}<p>foo".format(iframe("<p>bar"))))
> 
>     expected_text = ["foo", "bar"]
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch_webelement.py b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch_webelement.py
>index 89480b66b3a6..a30d2d8d339c 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch_webelement.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_frame/switch_webelement.py
>@@ -3,7 +3,6 @@ import pytest
> import webdriver.protocol as protocol
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline, iframe
> 
> 
> def switch_to_frame(session, frame):
>@@ -14,14 +13,14 @@ def switch_to_frame(session, frame):
>         session=session)
> 
> 
>-def frameset(*docs):
>+def frameset(inline, *docs):
>     frames = list(map(lambda doc: "<frame src='{}'></frame>".format(inline(doc)), docs))
>     return "<frameset rows='{}'>\n{}</frameset>".format(len(frames) * "*,", "\n".join(frames))
> 
> 
> @pytest.mark.parametrize("index, value", [[0, "foo"], [1, "bar"]])
>-def test_frame_id_webelement_frame(session, index, value):
>-    session.url = inline(frameset("<p>foo", "<p>bar"))
>+def test_frame_id_webelement_frame(session, inline, index, value):
>+    session.url = inline(frameset(inline, "<p>foo", "<p>bar"))
>     frames = session.find.css("frame")
>     assert len(frames) == 2
> 
>@@ -33,7 +32,7 @@ def test_frame_id_webelement_frame(session, index, value):
> 
> 
> @pytest.mark.parametrize("index, value", [[0, "foo"], [1, "bar"]])
>-def test_frame_id_webelement_iframe(session, index, value):
>+def test_frame_id_webelement_iframe(session, inline, iframe, index, value):
>     session.url = inline("{}{}".format(iframe("<p>foo"), iframe("<p>bar")))
>     frames = session.find.css("iframe")
>     assert len(frames) == 2
>@@ -45,7 +44,7 @@ def test_frame_id_webelement_iframe(session, index, value):
>     assert element.text == value
> 
> 
>-def test_frame_id_webelement_nested(session):
>+def test_frame_id_webelement_nested(session, inline, iframe):
>     session.url = inline(iframe("{}<p>foo".format(iframe("<p>bar"))))
> 
>     expected_text = ["foo", "bar"]
>@@ -58,7 +57,7 @@ def test_frame_id_webelement_nested(session):
>         assert element.text == expected_text[i]
> 
> 
>-def test_frame_id_webelement_no_element_reference(session):
>+def test_frame_id_webelement_no_element_reference(session, inline, iframe):
>     session.url = inline(iframe("<p>foo"))
>     frame = session.find.css("iframe", all=False)
>     frame.id = "bar"
>@@ -67,7 +66,7 @@ def test_frame_id_webelement_no_element_reference(session):
>     assert_error(response, "no such element")
> 
> 
>-def test_frame_id_webelement_stale_reference(session):
>+def test_frame_id_webelement_stale_reference(session, inline, iframe):
>     session.url = inline(iframe("<p>foo"))
>     frame = session.find.css("iframe", all=False)
> 
>@@ -77,9 +76,27 @@ def test_frame_id_webelement_stale_reference(session):
>     assert_error(response, "stale element reference")
> 
> 
>-def test_frame_id_webelement_no_frame_element(session):
>+def test_frame_id_webelement_no_frame_element(session, inline):
>     session.url = inline("<p>foo")
>     no_frame = session.find.css("p", all=False)
> 
>     response = switch_to_frame(session, no_frame)
>     assert_error(response, "no such frame")
>+
>+
>+def test_frame_id_webelement_cloned_into_iframe(session, inline, iframe):
>+    session.url = inline(iframe("<body><p>hello world</p></body>"))
>+
>+    session.execute_script("""
>+        const iframe = document.getElementsByTagName('iframe')[0];
>+        const div = document.createElement('div');
>+        div.innerHTML = 'I am a div created in top window and appended into the iframe';
>+        iframe.contentWindow.document.body.appendChild(div);
>+    """)
>+
>+    frame = session.find.css("iframe", all=False)
>+    response = switch_to_frame(session, frame)
>+    assert_success(response)
>+
>+    element = session.find.css("div", all=False)
>+    assert element.text == "I am a div created in top window and appended into the iframe"
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_parent_frame/switch.py b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_parent_frame/switch.py
>index ef2da45f1625..9c6db8d2cd61 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_parent_frame/switch.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_parent_frame/switch.py
>@@ -1,9 +1,8 @@
> import pytest
> 
>-from webdriver import StaleElementReferenceException
>+from webdriver import NoSuchElementException
> 
> from tests.support.asserts import assert_error, assert_success
>-from tests.support.inline import inline, iframe
> 
> 
> def switch_to_parent_frame(session):
>@@ -11,7 +10,7 @@ def switch_to_parent_frame(session):
>         "POST", "session/{session_id}/frame/parent".format(**vars(session)))
> 
> 
>-def test_null_response_value(session):
>+def test_null_response_value(session, inline, iframe):
>     session.url = inline(iframe("<p>foo"))
>     frame_element = session.find.css("iframe", all=False)
>     session.switch_frame(frame_element)
>@@ -21,7 +20,16 @@ def test_null_response_value(session):
>     assert value is None
> 
> 
>-def test_no_top_browsing_context(session, closed_window):
>+def test_no_top_browsing_context(session, url):
>+    session.window_handle = session.new_window()
>+
>+    session.url = url("/webdriver/tests/support/html/frames.html")
>+
>+    subframe = session.find.css("#sub-frame", all=False)
>+    session.switch_frame(subframe)
>+
>+    session.window.close()
>+
>     response = switch_to_parent_frame(session)
>     assert_error(response, "no such window")
> 
>@@ -49,19 +57,29 @@ def test_no_browsing_context(session, closed_frame):
>     session.find.css("#delete", all=False)
> 
> 
>-def test_stale_element_from_iframe(session):
>+def test_no_browsing_context_when_already_top_level(session, closed_window):
>+    response = switch_to_parent_frame(session)
>+    assert_error(response, "no such window")
>+
>+
>+def test_switch_from_iframe(session, inline, iframe):
>     session.url = inline(iframe("<p>foo"))
>     frame_element = session.find.css("iframe", all=False)
>     session.switch_frame(frame_element)
>-    stale_element = session.find.css("p", all=False)
>+    element = session.find.css("p", all=False)
> 
>     result = switch_to_parent_frame(session)
>     assert_success(result)
> 
>-    with pytest.raises(StaleElementReferenceException):
>-        stale_element.text
>+    with pytest.raises(NoSuchElementException):
>+        element.text
>+
> 
>+def test_switch_from_top_level(session, inline):
>+    session.url = inline("<p>foo")
>+    element = session.find.css("p", all=False)
> 
>-def test_switch_from_top_level(session):
>     result = switch_to_parent_frame(session)
>     assert_success(result)
>+
>+    assert element.text == "foo"
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_window/switch.py b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_window/switch.py
>index 98b4bee16e2d..28d432a8b5b4 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/switch_to_window/switch.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/switch_to_window/switch.py
>@@ -1,3 +1,6 @@
>+import pytest
>+
>+from webdriver.error import NoSuchElementException, NoSuchAlertException
> from webdriver.transport import Response
> 
> from tests.support.asserts import assert_error, assert_success
>@@ -51,3 +54,47 @@ def test_no_browsing_context(session, url):
>     assert_success(response)
> 
>     assert session.window_handle == new_handle
>+
>+
>+def test_switch_to_window_sets_top_level_context(session, inline, iframe):
>+    session.url = inline(iframe("<p>foo"))
>+
>+    frame = session.find.css("iframe", all=False)
>+    session.switch_frame(frame)
>+    session.find.css("p", all=False)
>+
>+    response = switch_to_window(session, session.window_handle)
>+    assert_success(response)
>+
>+    session.find.css("iframe", all=False)
>+
>+
>+def test_element_not_found_after_tab_switch(session, inline):
>+    session.url = inline("<p id='a'>foo")
>+    paragraph = session.find.css("p", all=False)
>+
>+    session.window_handle = session.new_window(type_hint="tab")
>+
>+    with pytest.raises(NoSuchElementException):
>+        paragraph.attribute("id")
>+
>+
>+@pytest.mark.parametrize("dialog_type", ["alert", "confirm", "prompt"])
>+def test_finds_exising_user_prompt_after_tab_switch(session, dialog_type):
>+    original_handle = session.window_handle
>+    new_handle = session.new_window()
>+
>+    session.execute_script("{}('foo');".format(dialog_type))
>+
>+    response = switch_to_window(session, new_handle)
>+    assert_success(response)
>+
>+    with pytest.raises(NoSuchAlertException):
>+        session.alert.text
>+
>+    session.window.close()
>+
>+    response = switch_to_window(session, original_handle)
>+    assert_success(response)
>+
>+    session.alert.accept()
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/iframe.py b/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/iframe.py
>index 83f55deff753..e7f1b0c8053d 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/iframe.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/iframe.py
>@@ -2,7 +2,6 @@ import pytest
> 
> from tests.support.asserts import assert_success
> from tests.support.image import png_dimensions
>-from tests.support.inline import iframe, inline
> 
> from . import element_dimensions
> 
>@@ -68,7 +67,7 @@ def take_element_screenshot(session, element_id):
>     )
> 
> 
>-def test_frame_element(session):
>+def test_frame_element(session, inline, iframe):
>     # Create a reference element which looks exactly like the frame's content
>     session.url = inline("{0}{1}".format(REFERENCE_STYLE, REFERENCE_CONTENT))
> 
>@@ -97,7 +96,7 @@ def test_frame_element(session):
> 
> 
> @pytest.mark.parametrize("domain", ["", "alt"], ids=["same_origin", "cross_origin"])
>-def test_source_origin(session, url, domain):
>+def test_source_origin(session, inline, iframe, domain):
>     # Create a reference element which looks exactly like the iframe
>     session.url = inline("{0}{1}".format(REFERENCE_STYLE, REFERENCE_CONTENT))
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/screenshot.py b/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/screenshot.py
>index 6ff6396edb2a..4d3bfb0e5c68 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/screenshot.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/screenshot.py
>@@ -1,6 +1,5 @@
> from tests.support.asserts import assert_error, assert_success
> from tests.support.image import png_dimensions
>-from tests.support.inline import inline
> 
> from . import element_dimensions
> 
>@@ -20,7 +19,7 @@ def test_no_top_browsing_context(session, closed_window):
>     assert_error(response, "no such window")
> 
> 
>-def test_no_browsing_context(session, closed_frame):
>+def test_no_browsing_context(session, closed_frame, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>@@ -30,7 +29,7 @@ def test_no_browsing_context(session, closed_frame):
>     assert png_dimensions(screenshot) == element_dimensions(session, element)
> 
> 
>-def test_stale(session):
>+def test_stale(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
>     session.refresh()
>@@ -39,7 +38,7 @@ def test_stale(session):
>     assert_error(result, "stale element reference")
> 
> 
>-def test_format_and_dimensions(session):
>+def test_format_and_dimensions(session, inline):
>     session.url = inline("<input>")
>     element = session.find.css("input", all=False)
> 
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/user_prompts.py
>index 5d1b497ff2c4..39fefe9325a9 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/take_element_screenshot/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_png, assert_success
>-from tests.support.inline import inline
> 
> 
> def take_element_screenshot(session, element_id):
>@@ -17,7 +16,7 @@ def take_element_screenshot(session, element_id):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input/>")
>         element = session.find.css("input", all=False)
>@@ -35,7 +34,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input/>")
>         element = session.find.css("input", all=False)
>@@ -51,7 +50,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input/>")
>         element = session.find.css("input", all=False)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/iframe.py b/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/iframe.py
>index 601c039d56de..81881c1dae73 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/iframe.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/iframe.py
>@@ -2,9 +2,8 @@ import pytest
> 
> from tests.support.asserts import assert_success
> from tests.support.image import png_dimensions
>-from tests.support.inline import iframe, inline
> 
>-from . import element_dimensions, viewport_dimensions
>+from . import viewport_dimensions
> 
> DEFAULT_CONTENT = "<div id='content'>Lorem ipsum dolor sit amet.</div>"
> 
>@@ -63,7 +62,7 @@ def take_screenshot(session):
>         "GET", "session/{session_id}/screenshot".format(**vars(session)))
> 
> 
>-def test_always_captures_top_browsing_context(session):
>+def test_always_captures_top_browsing_context(session, inline, iframe):
>     iframe_content = "{0}{1}".format(INNER_IFRAME_STYLE, DEFAULT_CONTENT)
>     session.url = inline("""{0}{1}""".format(OUTER_IFRAME_STYLE, iframe(iframe_content)))
> 
>@@ -82,7 +81,7 @@ def test_always_captures_top_browsing_context(session):
> 
> 
> @pytest.mark.parametrize("domain", ["", "alt"], ids=["same_origin", "cross_origin"])
>-def test_source_origin(session, domain):
>+def test_source_origin(session, inline, iframe, domain):
>     session.url = inline("{0}{1}".format(REFERENCE_STYLE, REFERENCE_CONTENT))
> 
>     response = take_screenshot(session)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/screenshot.py b/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/screenshot.py
>index d6130919167a..9e71a633c708 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/screenshot.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/screenshot.py
>@@ -1,6 +1,5 @@
> from tests.support.asserts import assert_error, assert_png, assert_success
> from tests.support.image import png_dimensions
>-from tests.support.inline import inline
> 
> from . import viewport_dimensions
> 
>@@ -15,7 +14,7 @@ def test_no_top_browsing_context(session, closed_window):
>     assert_error(response, "no such window")
> 
> 
>-def test_no_browsing_context(session, closed_frame):
>+def test_no_browsing_context(session, closed_frame, inline):
>     session.url = inline("<input>")
> 
>     response = take_screenshot(session)
>@@ -25,7 +24,7 @@ def test_no_browsing_context(session, closed_frame):
>     assert png_dimensions(value) == viewport_dimensions(session)
> 
> 
>-def test_format_and_dimensions(session):
>+def test_format_and_dimensions(session, inline):
>     session.url = inline("<input>")
> 
>     response = take_screenshot(session)
>diff --git a/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/user_prompts.py b/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/user_prompts.py
>index ad9e3695148d..7d57f8f2716b 100644
>--- a/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/user_prompts.py
>+++ b/WebDriverTests/imported/w3c/webdriver/tests/take_screenshot/user_prompts.py
>@@ -3,7 +3,6 @@
> import pytest
> 
> from tests.support.asserts import assert_dialog_handled, assert_error, assert_png, assert_success
>-from tests.support.inline import inline
> 
> 
> def take_screenshot(session):
>@@ -12,7 +11,7 @@ def take_screenshot(session):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_without_exception(session, create_dialog):
>+def check_user_prompt_closed_without_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_without_exception(dialog_type, retval):
>         session.url = inline("<input/>")
> 
>@@ -29,7 +28,7 @@ def check_user_prompt_closed_without_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_closed_with_exception(session, create_dialog):
>+def check_user_prompt_closed_with_exception(session, create_dialog, inline):
>     def check_user_prompt_closed_with_exception(dialog_type, retval):
>         session.url = inline("<input/>")
> 
>@@ -44,7 +43,7 @@ def check_user_prompt_closed_with_exception(session, create_dialog):
> 
> 
> @pytest.fixture
>-def check_user_prompt_not_closed_but_exception(session, create_dialog):
>+def check_user_prompt_not_closed_but_exception(session, create_dialog, inline):
>     def check_user_prompt_not_closed_but_exception(dialog_type):
>         session.url = inline("<input/>")
>

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Attachments on bug 230551: 438811 | 438943 | 438946 | 439024 | 439035 | 440486