MediaSourceEngine integration tests fail on Safari 10

[joeyparrish]

In Safari 10, MediaSourceEngine integration tests trigger failed assertions in MediaSourceEngine. Example:

Safari 10.0.1 (Mac OS X 10.12.1) MediaSourceEngine ends the stream, truncating the duration FAILED
	Failed: Spurious updateend event!
	jasmineAssert@test/test/boot.js:37:13
	onUpdateEnd_@lib/media/media_source_engine.js:682:22
	[native code]

This could indicate a bad assumption in MediaSourceEngine, an implementation bug in Safari, or a bad test. Needs investigation.

[joeyparrish]

Two bugs found in Safari 10's MSE implementation:

• https://bugs.webkit.org/show_bug.cgi?id=165336
• https://bugs.webkit.org/show_bug.cgi?id=165342