This CL clean up patch in SVGElements.

Source/core/svg/SVGDocumentExtensions.cpp

 /*
  * Copyright (C) 2006 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2007 Rob Buis <buis@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.
  *
@@ skipping 59 matching lines @@
 {
     if (id.isEmpty())
         return;
 
     m_resources.remove(id);
 }
 
 LayoutSVGResourceContainer* SVGDocumentExtensions::resourceById(const AtomicString& id) const
 {
     if (id.isEmpty())
-        return 0;
+        return nullptr;
 
     return m_resources.get(id);
 }
 
 void SVGDocumentExtensions::serviceOnAnimationFrame(Document& document, double monotonicAnimationStartTime)
 {
     if (!document.svgExtensions())
         return;
     document.accessSVGExtensions().serviceAnimations(monotonicAnimationStartTime);
 }
@@ skipping 178 matching lines @@
     ASSERT(!m_pendingResourcesForRemoval.contains(id));
 
     OwnPtrWillBeMember<SVGPendingElements> existing = m_pendingResources.take(id);
     if (existing && !existing->isEmpty())
         m_pendingResourcesForRemoval.add(id, existing.release());
 }
 
 Element* SVGDocumentExtensions::removeElementFromPendingResourcesForRemoval(const AtomicString& id)
 {
     if (id.isEmpty())
-        return 0;
+        return nullptr;
 
     SVGPendingElements* resourceSet = m_pendingResourcesForRemoval.get(id);
     if (!resourceSet || resourceSet->isEmpty())
-        return 0;
+        return nullptr;
 
     SVGPendingElements::iterator firstElement = resourceSet->begin();
     Element* element = *firstElement;
 
     resourceSet->remove(firstElement);
 
     if (resourceSet->isEmpty())
         removePendingResourceForRemoval(id);
 
     return element;
@@ skipping 63 matching lines @@
 #if ENABLE(OILPAN)
     visitor->trace(m_document);
     visitor->trace(m_timeContainers);
     visitor->trace(m_relativeLengthSVGRoots);
     visitor->trace(m_pendingResources);
     visitor->trace(m_pendingResourcesForRemoval);
 #endif
 }
 
 }