Use DEFINE_NODE_TYPE_CASTS instead of using manual toSVGFooElement()

Source/core/svg/SVGUseElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  * Copyright (C) 2011 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012 University of Szeged
  * Copyright (C) 2012 Renata Hodovan <reni@webkit.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 922 matching lines @@
         || heightCurrentValue().isRelative())
         return true;
 
     if (!m_targetElementInstance)
         return false;
 
     SVGElement* element = m_targetElementInstance->correspondingElement();
     if (!element)
         return false;
 
-    return toSVGElement(element)->hasRelativeLengths();
+    return element->hasRelativeLengths();
 }
 
 void SVGUseElement::notifyFinished(Resource* resource)
 {
     if (!inDocument())
         return;
 
     invalidateShadowTree();
     if (resource->errorOccurred())
         dispatchEvent(Event::create(EventTypeNames::error));
@@ skipping 38 matching lines @@
 
     if (m_resource)
         m_resource->removeClient(this);
 
     m_resource = resource;
     if (m_resource)
         m_resource->addClient(this);
 }
 
 }