DFW: Properly handle Esc key when the content is focused or when switching browser tabs.

props avryl.
fixes #28279.
Built from https://develop.svn.wordpress.org/trunk@28443


git-svn-id: http://core.svn.wordpress.org/trunk@28270 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/wp-fullscreen.js

@@ -510,10 +510,10 @@
 				}
 			});
 
-			$document.on( 'keydown.wp-fullscreen', function( event ) {
-				if ( 27 === event.which && s.visible ) { // Esc
+			$( window ).on( 'keyup', function( event ) {
+				// Turn fullscreen off when Esc is pressed.
+				if ( 27 === event.keyCode && s.visible ) {
 					api.off();
-					event.stopImmediatePropagation();
 				}
 			});