Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/svg/SVGFELightElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006 Rob Buis <buis@kde.org>
  * Copyright (C) 2005 Oliver Hunt <oliver@nerget.com>
  *
  * 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 57 matching lines @@
         if (isSVGFELightElement(*node))
             return toSVGFELightElement(node);
     }
     return 0;
 }
 
 PassRefPtr<LightSource> SVGFELightElement::findLightSource(const SVGElement* svgElement)
 {
     SVGFELightElement* lightNode = findLightElement(svgElement);
     if (!lightNode)
-        return 0;
+        return nullptr;
     return lightNode->lightSource();
 }
 
 bool SVGFELightElement::isSupportedAttribute(const QualifiedName& attrName)
 {
     DEFINE_STATIC_LOCAL(HashSet<QualifiedName>, supportedAttributes, ());
     if (supportedAttributes.isEmpty()) {
         supportedAttributes.add(SVGNames::azimuthAttr);
         supportedAttributes.add(SVGNames::elevationAttr);
         supportedAttributes.add(SVGNames::xAttr);
@@ skipping 89 matching lines @@
     if (!changedByParser) {
         if (ContainerNode* parent = parentNode()) {
             RenderObject* renderer = parent->renderer();
             if (renderer && renderer->isSVGResourceFilterPrimitive())
                 RenderSVGResource::markForLayoutAndParentResourceInvalidation(renderer);
         }
     }
 }
 
 }