TinyMCE: add support for audio and video shortcodes without closing, fix...

TinyMCE: add support for audio and video shortcodes without closing, fix jshint warning, see #27016.
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git-svn-id: https://core.svn.wordpress.org/trunk@27039 1a063a9b-81f0-0310-95a4-ce76da25c4cd