Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/dom/shadow/ShadowRoot.cpp

 /*
  * Copyright (C) 2011 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 111 matching lines @@
     if (type() != AuthorShadowRoot)
         return false;
     if (ShadowRoot* older = olderShadowRoot())
         return older->type() == UserAgentShadowRoot;
     return true;
 }
 
 PassRefPtr<Node> ShadowRoot::cloneNode(bool, ExceptionState& exceptionState)
 {
     exceptionState.throwDOMException(DataCloneError, "ShadowRoot nodes are not clonable.");
-    return 0;
+    return nullptr;
 }
 
 String ShadowRoot::innerHTML() const
 {
     return createMarkup(this, ChildrenOnly);
 }
 
 void ShadowRoot::setInnerHTML(const String& markup, ExceptionState& exceptionState)
 {
     if (isOrphan()) {
@@ skipping 332 matching lines @@
 {
     ensureShadowRootRareData()->setChildrenAffectedByFirstChildRules(true);
 }
 
 void ShadowRoot::setChildrenAffectedByLastChildRules()
 {
     ensureShadowRootRareData()->setChildrenAffectedByLastChildRules(true);
 }
 
 }