Customizer: Track the link that was used to open the customizer and restore focus on close. props lessbloat. fixes #21283.

git-svn-id: http://core.svn.wordpress.org/trunk@22756 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/customize-controls.js

@@ -881,9 +881,8 @@
 		$('.back').keydown( function( event ) {
 			if ( 9 === event.which ) // tab
 				return;
-			var thisHref = $(this).attr('href');
 			if ( 13 === event.which ) // enter
-				window.location = thisHref;
+				parent.send( 'close' );
 			event.preventDefault();
 		});