Twenty Thirteen: update JavaScript-based accessibility function hooked to `hashchange` event to verify user input correctly. Props mfields for the original patch.

Also add textarea to list of elements. See #23875.

git-svn-id: http://core.svn.wordpress.org/trunk@24070 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: avoid orphans in Aside date post meta. Props obenland, fixes #24166.

git-svn-id: http://core.svn.wordpress.org/trunk@24071 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: remove `hgroup` from the theme markup structure since it's been dropped from HTML5 spec. Props obenland for the starter patch. Fixes #24114.

git-svn-id: http://core.svn.wordpress.org/trunk@24072 1a063a9b-81f0-0310-95a4-ce76da25c4cd