Use DEFINE_NODE_TYPE_CASTS instead of using manual toSVGFooElement()

Source/core/svg/SVGHKernElement.h

 /*
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2008 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 25 matching lines @@
 
 private:
     SVGHKernElement(const QualifiedName&, Document&);
 
     virtual InsertionNotificationRequest insertedInto(ContainerNode*) OVERRIDE;
     virtual void removedFrom(ContainerNode*) OVERRIDE;
 
     virtual bool rendererIsNeeded(const RenderStyle&) { return false; }
 };
 
-inline SVGHKernElement* toSVGHKernElement(Node* node)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(SVGNames::hkernTag));
-    return static_cast<SVGHKernElement*>(node);
-}
+DEFINE_NODE_TYPE_CASTS(SVGHKernElement, hasTagName(SVGNames::hkernTag));
 
 } // namespace WebCore
 
 #endif // ENABLE(SVG_FONTS)
 #endif