Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/html/HTMLOptionElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2004, 2005, 2006, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2011 Motorola Mobility, Inc.  All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 50 matching lines @@
 
 PassRefPtr<HTMLOptionElement> HTMLOptionElement::createForJSConstructor(Document& document, const String& data, const AtomicString& value,
     bool defaultSelected, bool selected, ExceptionState& exceptionState)
 {
     RefPtr<HTMLOptionElement> element = adoptRef(new HTMLOptionElement(document));
 
     RefPtr<Text> text = Text::create(document, data.isNull() ? "" : data);
 
     element->appendChild(text.release(), exceptionState);
     if (exceptionState.hadException())
-        return 0;
+        return nullptr;
 
     if (!value.isNull())
         element->setValue(value);
     if (defaultSelected)
         element->setAttribute(selectedAttr, emptyAtom);
     element->setSelected(selected);
 
     return element.release();
 }
 
@@ skipping 287 matching lines @@
 
 HTMLFormElement* HTMLOptionElement::form() const
 {
     if (HTMLSelectElement* selectElement = ownerSelectElement())
         return selectElement->formOwner();
 
     return 0;
 }
 
 } // namespace WebCore