Test for abort and emptied events in HTMLMediaElement.load()

Thanks to Revlin John who submitted a similar test:
https://github.com/w3c/web-platform-tests/pull/571

This started out as improvments to that test, but quickly morphed beyond
recognition in an attempt to provide full coverage.

There's plenty of load() left to test, but that is better left to
dedicated tests since they will require more complex setup to e.g. get
in-band text tracks or seek in the video.
Add blank lines between tests
Merge and expand audio_004.htm and video_001.htm

The existing tests only test that the playing event is fired, also test
that for the other three events fired in the same section of the spec.

This revealed a bug in Blink/WebKit, where canplaythrough is fired before
play and playing.
Verify readyState and paused state when autoplaying

Simplify the title to just autoplay since the test is quite general now.
Remove duplicated and broken tests for src attribute removal

This is tested loading-the-media-resource/020.html with much less code.

Also, neither of the removed tests actually work, a local Blink build
where removing the src attribute does invoke resource selection still
passes both tests.
Skip appendChild (media elements need not be in a document to autoplay)
Remove redundant media reflection tests

These are all covered by html/dom/reflection-embedded.html
Remove mysterious audio reflection tests

These tests just look weird, and the spec reference goes nowhere.
add test on leap years and value sanitization algorithm
tests of max number of days
check month range
Merge pull request #636 from foolip/autoplay

Merge and expand audio_004.htm and video_001.htm
Rename manual media test to *-manual.html
Merge pull request #621 from foolip/load-algorithm-networkState

Test for abort and emptied events in HTMLMediaElement.load()
Merge pull request #638 from foolip/rm-duplicate-src-removal

Remove duplicated and broken tests for src attribute removal
Merge pull request #646 from foolip/rename-manual

Rename manual media test to *-manual.html
Merge four volumechange tests into a single more comprehensive one
Test for the non-support of <video audio=muted>
Merge pull request #639 from foolip/rm-duplicate-reflection

Remove redundant media reflection tests
add tests for input type=week