Add support to populate custom context menu items.

Source/platform/ContextMenu.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 22 matching lines @@
 
 namespace blink {
 
 class PLATFORM_EXPORT ContextMenu {
     WTF_MAKE_NONCOPYABLE(ContextMenu); WTF_MAKE_FAST_ALLOCATED;
 public:
     ContextMenu() { }
     const ContextMenuItem* itemWithAction(unsigned) const;
     const Vector<ContextMenuItem>& items() const { return m_items; }
     void appendItem(const ContextMenuItem& item) { m_items.append(item); }
+    void removeLastItem() { m_items.removeLast(); }
 
 private:
     Vector<ContextMenuItem> m_items;
 };
 
 }
 
 #endif // ContextMenu_h