Changing the mode of an in-band track to "showing" should make any current cue(s) visible immediately.
Created attachment 201372 [details]
Created attachment 201376 [details]
Skip new test on platforms that don't support in-band captions
Attachment 201376 [details] did not pass style-queue:
Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'LayoutTests/ChangeLog', u'LayoutTests/media/track/track-in-band-mode-expected.txt', u'LayoutTests/media/track/track-in-band-mode.html', u'LayoutTests/platform/efl/TestExpectations', u'LayoutTests/platform/gtk/TestExpectations', u'LayoutTests/platform/mac/TestExpectations', u'LayoutTests/platform/qt/TestExpectations', u'LayoutTests/platform/win/TestExpectations', u'Source/WebCore/ChangeLog', u'Source/WebCore/html/HTMLMediaElement.cpp']" exit_code: 1
LayoutTests/platform/mac/TestExpectations:1356: Did not find a test name. [test/expectations] 
Total errors found: 1 in 10 files
If any of these errors are false positives, please file a bug against check-webkit-style.
Created attachment 201377 [details]
Actually skip the test this time.