Make Event RefCountedGarbageCollected and implement trace() methods to the Event hierarcy

Source/core/events/KeyboardEvent.h

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 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.
@@ skipping 82 matching lines @@
     const PlatformKeyboardEvent* keyEvent() const { return m_keyEvent.get(); }
 
     virtual int keyCode() const OVERRIDE; // key code for keydown and keyup, character for keypress
     virtual int charCode() const OVERRIDE; // character code for keypress, 0 for keydown and keyup
     bool repeat() const { return m_isAutoRepeat; }
 
     virtual const AtomicString& interfaceName() const OVERRIDE;
     virtual bool isKeyboardEvent() const OVERRIDE;
     virtual int which() const OVERRIDE;
 
+    virtual void trace(Visitor*) OVERRIDE;
+
 private:
     KeyboardEvent();
     KeyboardEvent(const PlatformKeyboardEvent&, AbstractView*);
     KeyboardEvent(const AtomicString&, const KeyboardEventInit&);
     KeyboardEvent(const AtomicString& type, bool canBubble, bool cancelable, AbstractView*,
         const String& keyIdentifier, unsigned location,
         bool ctrlKey, bool altKey, bool shiftKey, bool metaKey, bool altGraphKey);
 
     OwnPtr<PlatformKeyboardEvent> m_keyEvent;
     String m_keyIdentifier;
     unsigned m_location;
     bool m_altGraphKey : 1;
     bool m_isAutoRepeat : 1;
 };
 
 class KeyboardEventDispatchMediator : public EventDispatchMediator {
 public:
     static PassRefPtr<KeyboardEventDispatchMediator> create(PassRefPtr<KeyboardEvent>);
 private:
     explicit KeyboardEventDispatchMediator(PassRefPtr<KeyboardEvent>);
     virtual bool dispatchEvent(EventDispatcher*) const OVERRIDE;
 };
 
 DEFINE_EVENT_TYPE_CASTS(KeyboardEvent);
 
 } // namespace WebCore
 
 #endif // KeyboardEvent_h