Give up on making uninterrupted hierarchies work in `get_page_children()` for now, reverts [30159], [30246], [30636].

Props boonebgorges.
See #14477.


git-svn-id: https://develop.svn.wordpress.org/trunk@30735 602fd350-edb4-49c9-b593-d223f7449a82
Monkey-patch MediaElement to restore H264 support to Chromium.

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

See #30281.


git-svn-id: https://develop.svn.wordpress.org/trunk@30736 602fd350-edb4-49c9-b593-d223f7449a82