Use DEFINE_NODE_TYPE_CASTS instead of using manual toSVGFooElement()

Source/core/svg/SVGFilterElement.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006 Rob Buis <buis@kde.org>
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  * Copyright (C) Research In Motion Limited 2010. 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 61 matching lines @@
         DECLARE_ANIMATED_LENGTH(Height, height)
         DECLARE_ANIMATED_INTEGER(FilterResX, filterResX)
         DECLARE_ANIMATED_INTEGER(FilterResY, filterResY)
         DECLARE_ANIMATED_STRING(Href, href)
         DECLARE_ANIMATED_BOOLEAN(ExternalResourcesRequired, externalResourcesRequired)
     END_DECLARE_ANIMATED_PROPERTIES
 
     HashSet<RefPtr<Node> > m_clientsToAdd;
 };
 
-inline SVGFilterElement* toSVGFilterElement(Node* node)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(SVGNames::filterTag));
-    return static_cast<SVGFilterElement*>(node);
-}
+DEFINE_NODE_TYPE_CASTS(SVGFilterElement, hasTagName(SVGNames::filterTag));
 
 }
 
 #endif