Implement checked attribute for menuitem.

Source/core/html/HTMLMenuItemElement.cpp

 // Copyright 2014 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.
 
 #include "config.h"
 #include "core/html/HTMLMenuItemElement.h"
 
 #include "core/HTMLNames.h"
+#include "core/events/Event.h"
 
 namespace blink {
 
+using namespace HTMLNames;
+
 inline HTMLMenuItemElement::HTMLMenuItemElement(Document& document)
     : HTMLElement(HTMLNames::menuitemTag, document)
 {
 }
 
+void HTMLMenuItemElement::defaultEventHandler(Event* event)
+{
+    if (event->type() == EventTypeNames::click) {
+        if (equalIgnoringCase(fastGetAttribute(typeAttr), "checkbox")) {
+            if (fastHasAttribute(checkedAttr))
+                removeAttribute(checkedAttr);
+            else
+                setAttribute(checkedAttr, "checked");
+        }
+        event->setDefaultHandled();
+    }
+}
+
 DEFINE_NODE_FACTORY(HTMLMenuItemElement)
 
 } // namespace blink