Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/css/resolver/MatchedPropertiesCache.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, 2013 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 31 matching lines @@
 
     // Note that we don't cache the original RenderStyle instance. It may be further modified.
     // The RenderStyle in the cache is really just a holder for the substructures and never used as-is.
     this->renderStyle = RenderStyle::clone(style);
     this->parentRenderStyle = RenderStyle::clone(parentStyle);
 }
 
 void CachedMatchedProperties::clear()
 {
     matchedProperties.clear();
-    renderStyle = 0;
-    parentRenderStyle = 0;
+    renderStyle = nullptr;
+    parentRenderStyle = nullptr;
 }
 
 MatchedPropertiesCache::MatchedPropertiesCache()
     : m_additionsSinceLastSweep(0)
     , m_sweepTimer(this, &MatchedPropertiesCache::sweep)
 {
 }
 
 const CachedMatchedProperties* MatchedPropertiesCache::find(unsigned hash, const StyleResolverState& styleResolverState, const MatchResult& matchResult)
 {
@@ skipping 99 matching lines @@
     // CSSPropertyInternalCallback sets the rule's selector name into the RenderStyle, and that's not recalculated if the RenderStyle is loaded from the cache, so don't cache it.
     if (!style->callbackSelectors().isEmpty())
         return false;
     // The cache assumes static knowledge about which properties are inherited.
     if (parentStyle->hasExplicitlyInheritedProperties())
         return false;
     return true;
 }
 
 }