C++11: Replace 0 with nullptr where applicable in layout code.

Source/core/layout/svg/ReferenceFilterBuilder.cpp

 /*
  * Copyright (C) 2013 Adobe Systems Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc.  All rights reserved.
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 24 matching lines @@
 #include "core/dom/Element.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/fetch/DocumentResource.h"
 #include "core/layout/svg/LayoutSVGResourceFilter.h"
 #include "core/svg/SVGDocumentExtensions.h"
 #include "core/svg/SVGFilterPrimitiveStandardAttributes.h"
 #include "core/svg/graphics/filters/SVGFilterBuilder.h"
 
 namespace blink {
 
-HashMap<const FilterOperation*, OwnPtr<DocumentResourceReference>>* ReferenceFilterBuilder::documentResourceReferences = 0;
+HashMap<const FilterOperation*, OwnPtr<DocumentResourceReference>>* ReferenceFilterBuilder::documentResourceReferences = nullptr;
 
 DocumentResourceReference* ReferenceFilterBuilder::documentResourceReference(const FilterOperation* filterOperation)
 {
     if (!documentResourceReferences)
-        return 0;
+        return nullptr;
 
     return documentResourceReferences->get(filterOperation);
 }
 
 void ReferenceFilterBuilder::setDocumentResourceReference(const FilterOperation* filterOperation, PassOwnPtr<DocumentResourceReference> documentResourceReference)
 {
     if (!documentResourceReferences)
         documentResourceReferences = new HashMap<const FilterOperation*, OwnPtr<DocumentResourceReference>>;
     documentResourceReferences->add(filterOperation, documentResourceReference);
 }
@@ skipping 72 matching lines @@
         effectElement->setStandardAttributes(effect.get());
         effect->setEffectBoundaries(SVGLengthContext::resolveRectangle<SVGFilterPrimitiveStandardAttributes>(effectElement, filterElement.primitiveUnits()->currentValue()->enumValue(), parentFilter->sourceImageRect()));
         EColorInterpolation colorInterpolation = colorInterpolationForElement(*effectElement, filterColorInterpolation);
         effect->setOperatingColorSpace(colorInterpolation == CI_LINEARRGB ? ColorSpaceLinearRGB : ColorSpaceDeviceRGB);
         builder->add(AtomicString(effectElement->result()->currentValue()->value()), effect);
     }
     return builder->lastEffect();
 }
 
 } // namespace blink