Have Node::document() return a reference instead of a pointer

Source/web/WebElement.cpp

 /*
  * Copyright (C) 2009 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 134 matching lines @@
     return WebString(constUnwrap<Element>()->computeInheritedLanguage());
 }
 
 void WebElement::requestFullScreen()
 {
     unwrap<Element>()->webkitRequestFullScreen(Element::ALLOW_KEYBOARD_INPUT);
 }
 
 WebDocument WebElement::document() const
 {
-    return WebDocument(constUnwrap<Element>()->document());
+    return WebDocument(&constUnwrap<Element>()->document());
 }
 
 WebRect WebElement::boundsInViewportSpace()
 {
     return unwrap<Element>()->boundsInRootViewSpace();
 }
 
 WebImage WebElement::imageContents()
 {
     if (isNull())
@@ skipping 20 matching lines @@
     m_private = elem;
     return *this;
 }
 
 WebElement::operator PassRefPtr<Element>() const
 {
     return toElement(m_private.get());
 }
 
 } // namespace WebKit