HTML 5.0 support

[azaozz]

All HTML 5.0 block tags have been added in both versions of wpautop(), even tags that aren't fully supported in any browser yet and as of [17625] TinyMCE recognizes all HTML 5.0 tags too.

This ticket is for correcting issues with the HTML 5.0 support in WordPress' general workflow (writing, editing, formatting) and writing testcases for it.

On the HTML 5 general workflow in WordPress:

http://core.trac.wordpress.org/browser/trunk/wp-includes/js/tinymce/plugins/wordpress/editor_plugin.dev.js#L192
List on "remove invalid parent paragraphs" might need updating.

http://core.trac.wordpress.org/browser/trunk/wp-admin/js/editor.dev.js#L37
http://core.trac.wordpress.org/browser/trunk/wp-admin/js/editor.dev.js#L59
blocklist1 and blocklist2 are HTML 5 unaware during switchEditors

Changing type to defect (bug) since that's what ticket is meant to collect.

Replying to WraithKenny:

List on "remove invalid parent paragraphs" might need updating.

I suspect this is fixed (not needed) in the current TinyMCE, needs a bit more testing before we take it out.

blocklist1 and blocklist2 are HTML 5 unaware during switchEditors

Needs more testing to confirm how to handle the new block element tags (and probably improve the current blocks that can contain another block).

related #14264

Related: #18534