Media Grid/Modal Keyboard navigation improvements:

* Add focus to arrows on Next/Previous in the grid's modal on left/right keypress, and add the necessary CSS for `:focus`
* When in a disabled input in the grid modal, allow the left/right keys to work
* Make the image editor return a `$.Deferred` so that there isn't a race condition with UI loading. 
* Assign focus when the edit image mode is rendered so that the modal can be closed on Esc press

Props wonderboymusic, adamsilverstein (for the initial patch).
See #23560.

Built from https://develop.svn.wordpress.org/trunk@29560


git-svn-id: http://core.svn.wordpress.org/trunk@29335 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/css/media-views-rtl.css

@@ -2717,6 +2717,12 @@
  *
  * This should be OOCSS'd so both use a shared selector.
  */
+.edit-attachment-frame {
+	display: block;
+	height: 100%;
+	width: 100%;
+}
+
 .edit-attachment-frame .edit-media-header {
 	overflow: hidden;
 }
@@ -2773,8 +2779,10 @@
 	font-weight: 300;
 }
 
+.edit-attachment-frame .edit-media-header .left:hover,
 .edit-attachment-frame .edit-media-header .right:hover,
-.edit-attachment-frame .edit-media-header .left:hover {
+.edit-attachment-frame .edit-media-header .left:focus,
+.edit-attachment-frame .edit-media-header .right:focus {
 	color: #2ea2cc;
 }
 

wp-includes/css/media-views.css

@@ -2717,6 +2717,12 @@
  *
  * This should be OOCSS'd so both use a shared selector.
  */
+.edit-attachment-frame {
+	display: block;
+	height: 100%;
+	width: 100%;
+}
+
 .edit-attachment-frame .edit-media-header {
 	overflow: hidden;
 }
@@ -2773,8 +2779,10 @@
 	font-weight: 300;
 }
 
+.edit-attachment-frame .edit-media-header .left:hover,
 .edit-attachment-frame .edit-media-header .right:hover,
-.edit-attachment-frame .edit-media-header .left:hover {
+.edit-attachment-frame .edit-media-header .left:focus,
+.edit-attachment-frame .edit-media-header .right:focus {
 	color: #2ea2cc;
 }