Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/css/StyleRule.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * (C) 2002-2003 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2002, 2005, 2006, 2008, 2012 Apple Inc. All rights reserved.
  *
  * 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 169 matching lines @@
         return toStyleRulePage(this)->copy();
     case FontFace:
         return toStyleRuleFontFace(this)->copy();
     case Media:
         return toStyleRuleMedia(this)->copy();
     case Supports:
         return toStyleRuleSupports(this)->copy();
     case Import:
         // FIXME: Copy import rules.
         ASSERT_NOT_REACHED();
-        return 0;
+        return nullptr;
     case Keyframes:
         return toStyleRuleKeyframes(this)->copy();
     case Viewport:
         return toStyleRuleViewport(this)->copy();
     case Filter:
         return toStyleRuleFilter(this)->copy();
     case Unknown:
     case Charset:
     case Keyframe:
         ASSERT_NOT_REACHED();
-        return 0;
+        return nullptr;
     }
     ASSERT_NOT_REACHED();
-    return 0;
+    return nullptr;
 }
 
 PassRefPtr<CSSRule> StyleRuleBase::createCSSOMWrapper(CSSStyleSheet* parentSheet, CSSRule* parentRule) const
 {
     RefPtr<CSSRule> rule;
     StyleRuleBase* self = const_cast<StyleRuleBase*>(this);
     switch (type()) {
     case Style:
         rule = CSSStyleRule::create(toStyleRule(self), parentSheet);
         break;
@@ skipping 18 matching lines @@
     case Viewport:
         rule = CSSViewportRule::create(toStyleRuleViewport(self), parentSheet);
         break;
     case Filter:
         rule = CSSFilterRule::create(toStyleRuleFilter(self), parentSheet);
         break;
     case Unknown:
     case Charset:
     case Keyframe:
         ASSERT_NOT_REACHED();
-        return 0;
+        return nullptr;
     }
     if (parentRule)
         rule->setParentRule(parentRule);
     return rule.release();
 }
 
 unsigned StyleRule::averageSizeInBytes()
 {
     return sizeof(StyleRule) + sizeof(CSSSelector) + StylePropertySet::averageSizeInBytes();
 }
@@ skipping 182 matching lines @@
         m_properties = m_properties->mutableCopy();
     return toMutableStylePropertySet(m_properties);
 }
 
 void StyleRuleFilter::setProperties(PassRefPtr<StylePropertySet> properties)
 {
     m_properties = properties;
 }
 
 } // namespace WebCore