Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/inspector/InspectorStyleSheet.h

 /*
  * Copyright (C) 2010, 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:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 69 matching lines @@
     bool isEmpty() const { return m_styleSheetId.isEmpty(); }
 
     const String& styleSheetId() const { return m_styleSheetId; }
     unsigned ordinal() const { return m_ordinal; }
 
     // ID type is either TypeBuilder::CSS::CSSStyleId or TypeBuilder::CSS::CSSRuleId.
     template<typename ID>
     PassRefPtr<ID> asProtocolValue() const
     {
         if (isEmpty())
-            return 0;
+            return nullptr;
 
         RefPtr<ID> result = ID::create()
             .setStyleSheetId(m_styleSheetId)
             .setOrdinal(m_ordinal);
         return result.release();
     }
 
 private:
     String m_styleSheetId;
     unsigned m_ordinal;
@@ skipping 188 matching lines @@
 
     // Contains "style" attribute value.
     mutable String m_styleText;
     mutable bool m_isStyleTextValid;
 };
 
 
 } // namespace WebCore
 
 #endif // !defined(InspectorStyleSheet_h)