Squashed 'wp/' changes from 54a3b49..d101cb3

d101cb3 Tag 3.9.1
c462d02 Use the same string on the about, credits, and freedoms screens.
01793d4 About 3.9.1
38b8a2f 3.9.1
f87cbbf Add missing Dashicons classes to User Admin menu.
3c530e4 3.9.1-RC1
e1f3459 Multisite: Treat 'www' as a special subdomain, reversing 3.9 regression.
d6656c5 Multisite: Fix case sensitivity regressions in 3.9.
dfb0e1a Custom header: Avoid warnings in the process_default_headers() method.
c51b634 Fix persistence of <track> elements in the body of a [video] shotcode in TinyMCE views.
8b65448 Refinements for asynchronous rendering in `wp.mce.media.PlaylistView`.
900f223 Customizer: Only tie header button action events to the header controls.
73a0918 Customizer: Avoid hiding 'Remove' buttons unrelated to custom headers.
c85dc97 Drag/drop on the editor to upload: don't trigger the uploader when selected text is being dragged from one window to another.
f2512c5 Avoid an expensive attachment counting query on the post editing screen.
524068c Add a compatibility layer in wp-playlist.js to avoid VM errors from MediaElement's plugin bridge in the TinyMCE views for playlists by suppressing playback for files whose mime-type is not supported in the user's browser natively.
daddadf Don't set the poster image for videos in a playlist if the image is the video mime-type icon blown up.
9753a18 Add calc() rules for max-width of playlist caption.
1745798 Properly account for text overflow in .wp-playlist-caption by adding display: block.
b4245bb Properly translate 'Select Poster Image'.
8649425 TinyMCE: fix the "active" state of the Link button when an image wrapped in a link is selected.
21796de TinyMCE: When adding a caption to an image that is in a paragraph with other text, move the caption node above the paragraph instead of below.
6e4bb1a Support RTL properly when displaying playlists.
0579fdb Media: Use the proper translated string for Video Playlist "drag info".
6b49e22 Rmove version string from Thickbox so it assumes the WP core version. Bust some caches.
f2f0f62 Alter the layout of the checkboxes in the modal view for Audio/Video Details to allow translations more room to breathe.
44c3913 TinyMCE: Restore old wordpress_adv_hidden editor parameter to enable force-showing the kitchen sink.
75c9032 Customizer: Allow to skip cropping header images if image width is smaller than or equal to theme width.
b5e12ae Shortcode JS: Avoid errors when an escaped shortcode includes a newline between brackets.
f690e6f Use '&mdash; Select &mdash;' instead of '-- Select --' for nav menus widget. Looks nicer.
2766c5f Simplify the admin menu notification selector so color schemes don't get stomped.
7aa8fbd Run WP_Editors::enqueue_scripts() on admin_print_footer_scripts, instead of admin_footer.
fba1c51 Don't allow disabled input styling to get lost in the cascade.
fe6fdac Fix cursor style for the resize handle of the editor.
653bc12 Ensure the editor height is saved properly as an integer.
df62215 Editor: Shrink the font size for the chosen format so it fits in more locales.
09e4a3c Force users to choose a nav menu in the custom nav menu widget, for a better customizer UX
3b0cc6d Recent Posts Widget: Use ob_end_flush() instead of ob_flush().
07e6c72 Version and POT file updates for bundled themes Twenty Eleven through Twenty Fourteen.
37d4b46 Theme Installer: Proper redirection and action links post-install in multisite.
3dd112e Fix logic inversion in [28124] to ensure widgets stay with themes during a theme switch.
0cecdcc The 3.9 branch is now 3.9.1-alpha.
REVERT: 54a3b49 Tag 3.9

git-subtree-dir: wp
git-subtree-split: d101cb394733f3a7d3fe6d935df0610ec2510057
Merge commit 'd2bce7d3fe39d938d5ceedd4ff68983f3053b83e'