REGRESSION(r263625): run-minibrowser fails on mac

[Philippe Normand]

$ Tools/Scripts/run-minibrowser --mac

AttributeError raised: 'list' object has no attribute 'startswith'
Traceback (most recent call last):
  File "/Users/philn/WebKit/Tools/Scripts/webkitpy/minibrowser/run_webkit_app.py", line 59, in main
    return port.run_minibrowser(args)
  File "/Users/philn/WebKit/Tools/Scripts/webkitpy/port/base.py", line 1372, in run_minibrowser
    return self._run_script(["old-run-minibrowser", ] + args)
  File "/Users/philn/WebKit/Tools/Scripts/webkitpy/port/base.py", line 1486, in _run_script
    run_script_command = [self.path_to_script(script_name)]
  File "/Users/philn/WebKit/Tools/Scripts/webkitpy/port/base.py", line 717, in path_to_script
    return self._webkit_finder.path_to_script(script_name)
  File "/Users/philn/WebKit/Tools/Scripts/webkitpy/common/webkit_finder.py", line 64, in path_to_script
    return self._filesystem.join("Tools", "Scripts", script_name)
  File "/Users/philn/WebKit/Tools/Scripts/webkitpy/common/system/filesystem.py", line 162, in join
    return os.path.join(*comps)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/posixpath.py", line 68, in join
    if b.startswith('/'):
AttributeError: 'list' object has no attribute 'startswith'

[Philippe Normand]

Created attachment 403351 [details]
Patch

[EWS]

Committed r263848: <https://trac.webkit.org/changeset/263848>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 403351 [details].

[Radar WebKit Bug Importer]

<rdar://problem/65037915>