Monkey-patch MediaElement to restore H264 support to Chromium.

Documented here:
https://core.trac.wordpress.org/ticket/30281#comment:9

See #30281.

Built from https://develop.svn.wordpress.org/trunk@30736


git-svn-id: http://core.svn.wordpress.org/trunk@30726 1a063a9b-81f0-0310-95a4-ce76da25c4cd