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

Source/core/events/GestureEvent.h

 /*
  * Copyright (C) 2012 Google 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:
  *  * Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *  * Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 27 matching lines @@
 
     static PassRefPtr<GestureEvent> create(PassRefPtr<AbstractView>, const PlatformGestureEvent&);
 
     virtual bool isGestureEvent() const OVERRIDE;
 
     virtual const AtomicString& interfaceName() const OVERRIDE;
 
     float deltaX() const { return m_deltaX; }
     float deltaY() const { return m_deltaY; }
 
+    virtual void trace(Visitor*) OVERRIDE;
+
 private:
     GestureEvent();
     GestureEvent(const AtomicString& type, PassRefPtr<AbstractView>, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey, float deltaX, float deltaY);
 
     float m_deltaX;
     float m_deltaY;
 };
 
 class GestureEventDispatchMediator FINAL : public EventDispatchMediator {
 public:
     static PassRefPtr<GestureEventDispatchMediator> create(PassRefPtr<GestureEvent> gestureEvent)
     {
         return adoptRef(new GestureEventDispatchMediator(gestureEvent));
     }
 
 private:
     explicit GestureEventDispatchMediator(PassRefPtr<GestureEvent>);
 
     GestureEvent* event() const;
 
     virtual bool dispatchEvent(EventDispatcher*) const OVERRIDE;
 };
 
 DEFINE_EVENT_TYPE_CASTS(GestureEvent);
 
 } // namespace WebCore
 
 #endif // GestureEvent_h