Use DEFINE_NODE_TYPE_CASTS instead of using manual toSVGFooElement()

Source/core/svg/SVGMaskElement.h

 /*
  * Copyright (C) 2005 Alexander Kellett <lypanov@kde.org>
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 50 matching lines @@
         DECLARE_ANIMATED_LENGTH(Height, height)
         DECLARE_ANIMATED_BOOLEAN(ExternalResourcesRequired, externalResourcesRequired)
     END_DECLARE_ANIMATED_PROPERTIES
 
     // SVGTests
     virtual void synchronizeRequiredFeatures() { SVGTests::synchronizeRequiredFeatures(this); }
     virtual void synchronizeRequiredExtensions() { SVGTests::synchronizeRequiredExtensions(this); }
     virtual void synchronizeSystemLanguage() { SVGTests::synchronizeSystemLanguage(this); }
 };
 
-inline SVGMaskElement* toSVGMaskElement(Node* node)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(SVGNames::maskTag));
-    return static_cast<SVGMaskElement*>(node);
-}
+DEFINE_NODE_TYPE_CASTS(SVGMaskElement, hasTagName(SVGNames::maskTag));
 
 }
 
 #endif