Use hidden attribute rather the 'display: none' for hiding menus.

chrome/browser/resources/shared/js/cr/ui/context_menu_handler.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 cr.define('cr.ui', function() {
 
   /** @const */ var Menu = cr.ui.Menu;
 
   /**
    * Handles context menus.
@@ skipping 13 matching lines @@
     },
 
     /**
      * Shows a menu as a context menu.
      * @param {!Event} e The event triggering the show (usually a contextmenu
      *     event).
      * @param {!cr.ui.Menu} menu The menu to show.
      */
     showMenu: function(e, menu) {
       this.menu_ = menu;
+      menu.hidden = false;
 
-      menu.style.display = 'block';
       // when the menu is shown we steal all keyboard events.
       var doc = menu.ownerDocument;
       doc.addEventListener('keydown', this, true);
       doc.addEventListener('mousedown', this, true);
       doc.addEventListener('blur', this, true);
       doc.defaultView.addEventListener('resize', this);
       menu.addEventListener('contextmenu', this);
       menu.addEventListener('activate', this);
       this.positionMenu_(e, menu);
     },
 
     /**
      * Hide the currently shown menu.
      */
     hideMenu: function() {
       var menu = this.menu;
       if (!menu)
         return;
 
-      menu.style.display = 'none';
+      menu.hidden = true;
       var doc = menu.ownerDocument;
       doc.removeEventListener('keydown', this, true);
       doc.removeEventListener('mousedown', this, true);
       doc.removeEventListener('blur', this, true);
       doc.defaultView.removeEventListener('resize', this);
       menu.removeEventListener('contextmenu', this);
       menu.removeEventListener('activate', this);
       menu.selectedIndex = -1;
       this.menu_ = null;
 
@@ skipping 164 matching lines @@
    * The singleton context menu handler.
    * @type {!ContextMenuHandler}
    */
   var contextMenuHandler = new ContextMenuHandler;
 
   // Export
   return {
     contextMenuHandler: contextMenuHandler
   };
 });