Restore the duck punch of TinyMCE's schema from [23120], along with updated...

Restore the duck punch of TinyMCE's schema from [23120], along with updated rules for all HTML5 elements, as painstakingly audited against the HTML5 spec.

Remove conflicting and unnecessary code in the WP TinyMCE plugin.

Fixes all known regressions when working with the embed, object, video, audio, source, and param elements in TinyMCE.

props markjaquith, koopersmith.
fixes #22790, #22842.
fixes #22842.



git-svn-id: https://core.svn.wordpress.org/trunk@23153 1a063a9b-81f0-0310-95a4-ce76da25c4cd