Media: Hide sidebar in Create Gallery when no actions available.

Check whether the media frame menu has action items. If not, hide the sidebar. Prevents showing a sidebar that looks interactive but contains no controls that are interactive. When in Create Gallery mode, the only action available is 'Create Gallery', and it is always active.

Props ukdrahul, ababir, ruchirj, nhrrob, joedolson, shailu25, mukesh27, sudipatel007, dhrumilk.
Fixes #60666.

git-svn-id: https://develop.svn.wordpress.org/trunk@59139 602fd350-edb4-49c9-b593-d223f7449a82

src/js/media/controllers/state.js

@@ -165,17 +165,15 @@ var State = Backbone.Model.extend(/** @lends wp.media.controller.State.prototype
 	_menu: function() {
 		var menu = this.frame.menu,
 			mode = this.get('menu'),
-			actionMenuItems,
-			actionMenuLength,
-			view;
+			view,
+			actionMenuItems = this.frame.menu.get('views'),
+			actionMenuLength = actionMenuItems ? actionMenuItems.views.get().length : 0;
 
 		if ( this.frame.menu ) {
-			actionMenuItems = this.frame.menu.get('views'),
-			actionMenuLength = actionMenuItems ? actionMenuItems.views.get().length : 0,
 			// Show action menu only if it is active and has more than one default element.
 			this.frame.$el.toggleClass( 'hide-menu', ! mode || actionMenuLength < 2 );
 		}
-		if ( ! mode ) {
+		if ( ! mode || actionMenuLength < 2 ) {
 			return;
 		}