Introduce toSVGUseElement(), use it

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 252 matching lines @@
         buildPendingResource();
 }
 
 #ifdef DUMP_INSTANCE_TREE
 static void dumpInstanceTree(unsigned int& depth, String& text, SVGElementInstance* targetInstance)
 {
     SVGElement* element = targetInstance->correspondingElement();
     ASSERT(element);
 
     if (element->hasTagName(SVGNames::useTag)) {
-        if (static_cast<SVGUseElement*>(element)->cachedDocumentIsStillLoading())
+        if (toSVGUseElement(element)->cachedDocumentIsStillLoading())
             return;
     }
 
     SVGElement* shadowTreeElement = targetInstance->shadowTreeElement();
     ASSERT(shadowTreeElement);
 
     SVGUseElement* directUseElement = targetInstance->directUseElement();
     String directUseElementName = directUseElement ? directUseElement->nodeName() : "null";
 
     String elementId = element->getIdAttribute();
@@ skipping 288 matching lines @@
 void SVGUseElement::buildInstanceTree(SVGElement* target, SVGElementInstance* targetInstance, bool& foundProblem, bool foundUse)
 {
     ASSERT(target);
     ASSERT(targetInstance);
 
     // Spec: If the referenced object is itself a 'use', or if there are 'use' subelements within the referenced
     // object, the instance tree will contain recursive expansion of the indirect references to form a complete tree.
     bool targetHasUseTag = target->hasTagName(SVGNames::useTag);
     SVGElement* newTarget = 0;
     if (targetHasUseTag) {
-        foundProblem = hasCycleUseReferencing(static_cast<SVGUseElement*>(target), targetInstance, newTarget);
+        foundProblem = hasCycleUseReferencing(toSVGUseElement(target), targetInstance, newTarget);
         if (foundProblem)
             return;
 
         // We only need to track first degree <use> dependencies. Indirect references are handled
         // as the invalidation bubbles up the dependency chain.
         if (!foundUse) {
             ASSERT(document());
             document()->accessSVGExtensions()->addElementReferencingTarget(this, target);
             foundUse = true;
         }
@@ skipping 25 matching lines @@
 
         // Enter recursion, appending new instance tree nodes to the "instance" object.
         buildInstanceTree(element, instancePtr, foundProblem, foundUse);
         if (foundProblem)
             return;
     }
 
     if (!targetHasUseTag || !newTarget)
         return;
 
-    RefPtr<SVGElementInstance> newInstance = SVGElementInstance::create(this, static_cast<SVGUseElement*>(target), newTarget);
+    RefPtr<SVGElementInstance> newInstance = SVGElementInstance::create(this, toSVGUseElement(target), newTarget);
     SVGElementInstance* newInstancePtr = newInstance.get();
     targetInstance->appendChild(newInstance.release());
     buildInstanceTree(newTarget, newInstancePtr, foundProblem, foundUse);
 }
 
 bool SVGUseElement::hasCycleUseReferencing(SVGUseElement* use, SVGElementInstance* targetInstance, SVGElement*& newTarget)
 {
     Element* targetElement = SVGURIReference::targetElementFromIRIString(use->hrefCurrentValue(), referencedDocument());
     newTarget = 0;
     if (targetElement && targetElement->isSVGElement())
@@ skipping 56 matching lines @@
 void SVGUseElement::expandUseElementsInShadowTree(Node* element)
 {
     // Why expand the <use> elements in the shadow tree here, and not just
     // do this directly in buildShadowTree, if we encounter a <use> element?
     //
     // Short answer: Because we may miss to expand some elements. Ie. if a <symbol>
     // contains <use> tags, we'd miss them. So once we're done with settin' up the
     // actual shadow tree (after the special case modification for svg/symbol) we have
     // to walk it completely and expand all <use> elements.
     if (element->hasTagName(SVGNames::useTag)) {
-        SVGUseElement* use = static_cast<SVGUseElement*>(element);
+        SVGUseElement* use = toSVGUseElement(element);
         ASSERT(!use->cachedDocumentIsStillLoading());
 
         Element* targetElement = SVGURIReference::targetElementFromIRIString(use->hrefCurrentValue(), referencedDocument());
         SVGElement* target = 0;
         if (targetElement && targetElement->isSVGElement())
             target = toSVGElement(targetElement);
 
         // Don't ASSERT(target) here, it may be "pending", too.
         // Setup sub-shadow tree root node
         RefPtr<SVGGElement> cloneParent = SVGGElement::create(SVGNames::gTag, referencedDocument());
@@ skipping 267 matching lines @@
 
     if (m_cachedDocument)
         m_cachedDocument->removeClient(this);
 
     m_cachedDocument = cachedDocument;
     if (m_cachedDocument)
         m_cachedDocument->addClient(this);
 }
 
 }