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

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

Index: chrome/browser/resources/shared/js/cr/ui/context_menu_handler.js
diff --git a/chrome/browser/resources/shared/js/cr/ui/context_menu_handler.js b/chrome/browser/resources/shared/js/cr/ui/context_menu_handler.js
index b478acee474178a7547175375d1ed07680fba3a3..696bb73431ccc1f223f3188189314c607655fe2a 100644
--- a/chrome/browser/resources/shared/js/cr/ui/context_menu_handler.js
+++ b/chrome/browser/resources/shared/js/cr/ui/context_menu_handler.js
@@ -31,8 +31,8 @@ cr.define('cr.ui', function() {
      */
     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);
@@ -52,7 +52,7 @@ cr.define('cr.ui', function() {
       if (!menu)
         return;
 
-      menu.style.display = 'none';
+      menu.hidden = true;
       var doc = menu.ownerDocument;
       doc.removeEventListener('keydown', this, true);
       doc.removeEventListener('mousedown', this, true);