* Do not change media element ready state when network response is complete.
* Do not fire multiple error events for the same media content.
* Inform media backend when media response is complete.
* Continue delaying the load event when a complete media response is received.
* Only mark a media response as complete when the response is the active one.
* Update expectations for imagebitmap tests using video element.
* Update fetch ORB video test expectations.
* Update media CSS selector test expectation for non-implemented feature.
* Update expectations for media element tests that now work.
* Updat expected result for failing reftest.
* Update expected failure for test that loads an audio file in a video element.
* Update media test expectation for unimplemented track feature.
* Do not process media element ready state changes that are unchanged.
* Reset media element ready state to Current when playback finishes.
* Set media element ready state to Enough when appropriate player event is received.
* Update test expectations.
Most tests were only being run for layout-2013, not for layout-2020.
This wasn't great since layout-2020 is now the default.
So this patch unifies the lists of included tests for both layouts.
For layout-2013 this implies adding css/css-content/, css/css-logical/
and css/css-masking/clip/.
For layout-2020 this implies adding several additional css tests, and
also tests like dom/, js/, html/, etc.
