Use DEFINE_NODE_TYPE_CASTS instead of using manual toHTMLFooElement()

Source/core/html/HTMLPlugInElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2008, 2009, 2012 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 85 matching lines @@
     virtual bool isKeyboardFocusable() const OVERRIDE;
     virtual bool isPluginElement() const;
 
     mutable ScriptInstance m_instance;
     NPObject* m_NPObject;
     bool m_isCapturingMouseEvents;
     bool m_inBeforeLoadEventHandler;
     DisplayState m_displayState;
 };
 
-inline HTMLPlugInElement* toHTMLPlugInElement(Node* node)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->isPluginElement());
-    return static_cast<HTMLPlugInElement*>(node);
-}
-
-inline const HTMLPlugInElement* toHTMLPlugInElement(const Node* node)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->isPluginElement());
-    return static_cast<const HTMLPlugInElement*>(node);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toHTMLPlugInElement(const HTMLPlugInElement*);
+DEFINE_NODE_TYPE_CASTS(HTMLPlugInElement, isPluginElement());
 
 } // namespace WebCore
 
 #endif // HTMLPlugInElement_h