[macOS debug] Layout Test imported/w3c/web-platform-tests/media-source/SourceBuffer-abort-readyState.html is a flaky failure

[Ryan Haddad]

The following layout test is flaky on macOS debug bots

imported/w3c/web-platform-tests/media-source/SourceBuffer-abort-readyState.html

Probable cause:

Unknown, this test has been flaky for a while.

Flakiness Dashboard:

https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=imported%2Fw3c%2Fweb-platform-tests%2Fmedia-source%2FSourceBuffer-abort-readyState.html

The test usually completes less than 2 seconds, but intermittently times out after 135 seconds with the following diff:

--- /Volumes/Data/slave/sierra-debug-tests-wk2/build/layout-test-results/imported/w3c/web-platform-tests/media-source/SourceBuffer-abort-readyState-expected.txt
+++ /Volumes/Data/slave/sierra-debug-tests-wk2/build/layout-test-results/imported/w3c/web-platform-tests/media-source/SourceBuffer-abort-readyState-actual.txt
@@ -1,4 +1,7 @@
+CONSOLE MESSAGE: line 51: InvalidStateError: The object is in an invalid state.
+
+Harness Error (FAIL), message = InvalidStateError: The object is in an invalid state.
 
 FAIL SourceBuffer#abort() (video/webm; codecs="vorbis,vp8") : If the readyState attribute of the parent media source is not in the "open" state then throw an INVALID_STATE_ERR exception and abort these steps. assert_unreached: Browser doesn't support the MIME used in this test: video/webm; codecs="vorbis,vp8" Reached unreachable code
-PASS SourceBuffer#abort() (video/mp4) : If the readyState attribute of the parent media source is not in the "open" state then throw an INVALID_STATE_ERR exception and abort these steps. 
+TIMEOUT SourceBuffer#abort() (video/mp4) : If the readyState attribute of the parent media source is not in the "open" state then throw an INVALID_STATE_ERR exception and abort these steps. Test timed out

[Truitt Savell]

Issue still occurring. 

easily can reproduce issue with a debug build and running with:

run-webkit-tests --root debug-235460 imported/w3c/web-platform-tests/media-source/SourceBuffer-abort-readyState.html --iterations 500 -f --debug

[Radar WebKit Bug Importer]

<rdar://problem/61471458>

[Jacob Uphoff]

Test is still flaky failing.

[Jacob Uphoff]

Set expectations for this here: https://trac.webkit.org/changeset/259749/webkit