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

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

Index: chrome/browser/resources/shared/js/cr/ui/menu_button.js
diff --git a/chrome/browser/resources/shared/js/cr/ui/menu_button.js b/chrome/browser/resources/shared/js/cr/ui/menu_button.js
index 5128c5dae56f0de7b669aee0d0f1fb2bfc69feea..09d17e5c44f3abfa927a873795b54ec5d647b1b0 100644
--- a/chrome/browser/resources/shared/js/cr/ui/menu_button.js
+++ b/chrome/browser/resources/shared/js/cr/ui/menu_button.js
@@ -113,7 +113,7 @@ cr.define('cr.ui', function() {
     showMenu: function() {
       this.hideMenu();
 
-      this.menu.style.display = 'block';
+      this.menu.hidden = false;
       this.setAttribute('menu-shown', '');
 
       // when the menu is shown we steal all keyboard events.
@@ -136,7 +136,7 @@ cr.define('cr.ui', function() {
         return;
 
       this.removeAttribute('menu-shown');

[arv (Not doing code reviews), 2012/05/08 21:46:25]

I think we can remove this attribute now since hidden is an attribute that we
can select on.

[Patrick Dubroy, 2012/05/09 14:39:35]

I think we still need it for styling. There are a bunch of CSS rules that use
it, and I don't think there's an easy way to change them so that they don't.

-      this.menu.style.display = 'none';
+      this.menu.hidden = true;
 
       this.showingEvents_.removeAll();
       this.menu.selectedIndex = -1;