Implement contextmenu attribute with basic support of <menu>

Source/core/html/HTMLMenuElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef HTMLMenuElement_h
 #define HTMLMenuElement_h
 
+#include "core/html/CustomContextMenuProvider.h"
 #include "core/html/HTMLElement.h"
+#include "core/page/ContextMenuProvider.h"
+#include "platform/ContextMenu.h"
+#include "platform/ContextMenuItem.h"
 
 namespace WebCore {
 
+class HTMLMenuElement;
+class CustomContextMenuProvider;
+
 class HTMLMenuElement FINAL : public HTMLElement {
 public:
     static PassRefPtrWillBeRawPtr<HTMLMenuElement> create(Document&);
 
+    virtual void defaultEventHandler(Event*) OVERRIDE;
+
+    CustomContextMenuProvider* menuProvider() { return m_menuProvider.get(); }
+    CustomContextMenuProvider& ensureMenuProvider();
+    void populateContextMenuItems(HTMLMenuElement*, ContextMenu&);
+    HTMLElement* menuItemAt(unsigned menuId);
+    HTMLElement * subjectElement() { return m_subject.get(); }
+
 private:
     explicit HTMLMenuElement(Document&);
+    RefPtr<CustomContextMenuProvider> m_menuProvider;
+    RefPtr<HTMLElement> m_subject;
+    Vector<HTMLElement*> m_menuItems;
 };
 
 } //namespace
 
 #endif