Theme installer:
 * Restore the feature filter.
 * Improve responsiveness.
 * Router updates, fixes.
 * Make "Upload Theme" button more consistent with the admin.
 * Avoid theme-count causing filters to jump.

props matveb.
see #27055.

Built from https://develop.svn.wordpress.org/trunk@27636


git-svn-id: http://core.svn.wordpress.org/trunk@27479 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fourteen: add Audio, Video, and Gallery Styles to editor styles. Props celloexpressions, see #27462.
Built from https://develop.svn.wordpress.org/trunk@27637


git-svn-id: http://core.svn.wordpress.org/trunk@27480 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: add Audio, Video, and Gallery Styles to editor styles. Props celloexpressions, see #27462.
Built from https://develop.svn.wordpress.org/trunk@27638


git-svn-id: http://core.svn.wordpress.org/trunk@27481 1a063a9b-81f0-0310-95a4-ce76da25c4cd
3.9-beta2

Built from https://develop.svn.wordpress.org/trunk@27639


git-svn-id: http://core.svn.wordpress.org/trunk@27482 1a063a9b-81f0-0310-95a4-ce76da25c4cd