Cleanup: Add more conversion helpers for usage.

Source/core/events/WheelEvent.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, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Samsung Electronics. 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
@@ skipping 96 matching lines @@
     IntPoint m_wheelDelta;
     double m_deltaX;
     double m_deltaY;
     double m_deltaZ;
     unsigned m_deltaMode;
     bool m_directionInvertedFromDevice;
 };
 
 inline WheelEvent* toWheelEvent(Event* event)
 {
-    ASSERT(event && event->isWheelEvent());
+    ASSERT_WITH_SECURITY_IMPLICATION(!event || event->isWheelEvent());
     return static_cast<WheelEvent*>(event);
 }
 
 class WheelEventDispatchMediator : public EventDispatchMediator {
 public:
     static PassRefPtr<WheelEventDispatchMediator> create(const PlatformWheelEvent&, PassRefPtr<AbstractView>);
 private:
     WheelEventDispatchMediator(const PlatformWheelEvent&, PassRefPtr<AbstractView>);
     WheelEvent* event() const;
     virtual bool dispatchEvent(EventDispatcher*) const OVERRIDE;
 };
 
 } // namespace WebCore
 
 #endif // WheelEvent_h