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

Source/core/html/HTMLTableRowElement.cpp

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2010 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
@@ skipping 109 matching lines @@
 
 PassRefPtr<HTMLElement> HTMLTableRowElement::insertCell(int index, ExceptionState& es)
 {
     RefPtr<HTMLCollection> children = cells();
     int numCells = children ? children->length() : 0;
     if (index < -1 || index > numCells) {
         es.throwDOMException(IndexSizeError);
         return 0;
     }
 
-    RefPtr<HTMLTableCellElement> cell = HTMLTableCellElement::create(tdTag, document());
+    RefPtr<HTMLTableCellElement> cell = HTMLTableCellElement::create(tdTag, &document());
     if (index < 0 || index >= numCells)
         appendChild(cell, es);
     else {
         Node* n;
         if (index < 1)
             n = firstChild();
         else
             n = children->item(index);
         insertBefore(cell, n, es);
     }
@@ skipping 18 matching lines @@
 {
     return ensureCachedHTMLCollection(TRCells);
 }
 
 void HTMLTableRowElement::setCells(HTMLCollection*, ExceptionState& es)
 {
     es.throwDOMException(NoModificationAllowedError);
 }
 
 }