Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/css/RuleFeature.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 192 matching lines @@
 }
 
 bool RuleFeatureSet::classInvalidationRequiresSubtreeRecalc(const AtomicString& className)
 {
     DescendantInvalidationSet* set = m_classInvalidationSets.get(className);
     return set && set->wholeSubtreeInvalid();
 }
 
 DescendantInvalidationSet& RuleFeatureSet::ensureClassInvalidationSet(const AtomicString& className)
 {
-    InvalidationSetMap::AddResult addResult = m_classInvalidationSets.add(className, 0);
+    InvalidationSetMap::AddResult addResult = m_classInvalidationSets.add(className, nullptr);
     if (addResult.isNewEntry)
         addResult.storedValue->value = DescendantInvalidationSet::create();
     return *addResult.storedValue->value;
 }
 
 void RuleFeatureSet::collectFeaturesFromSelector(const CSSSelector& selector)
 {
     collectFeaturesFromSelector(selector, m_metadata, ProcessClasses);
 }
 
@@ skipping 240 matching lines @@
     }
 
     invalidationClasses.remove(oldSize, invalidationClasses.size() - oldSize);
     element->clearChildNeedsStyleInvalidation();
     element->clearNeedsStyleInvalidation();
 
     return thisElementNeedsStyleRecalc;
 }
 
 } // namespace WebCore