[mediasource-sourcebuffer-trackdefaults.html]
[Test round-trip of empty SourceBuffer.trackDefaults]
expected: FAIL
[Test round-trip of non-empty SourceBuffer.trackDefaults]
expected: FAIL
[Test setting trackDefaults on an already-removed SourceBuffer]
expected: FAIL
[Test setting trackDefaults on a SourceBuffer that is updating]
expected: FAIL
[Test setting null SourceBuffer.trackDefaults]
expected: FAIL