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

Source/core/editing/RemoveNodePreservingChildrenCommand.cpp

 /*
  * Copyright (C) 2005, 2008 Apple 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 14 matching lines @@
 
 #include "config.h"
 #include "core/editing/RemoveNodePreservingChildrenCommand.h"
 
 #include "core/dom/Node.h"
 #include "wtf/Assertions.h"
 
 namespace WebCore {
 
 RemoveNodePreservingChildrenCommand::RemoveNodePreservingChildrenCommand(PassRefPtr<Node> node, ShouldAssumeContentIsAlwaysEditable shouldAssumeContentIsAlwaysEditable)
-    : CompositeEditCommand(node->document())
+    : CompositeEditCommand(&node->document())
     , m_node(node)
     , m_shouldAssumeContentIsAlwaysEditable(shouldAssumeContentIsAlwaysEditable)
 {
     ASSERT(m_node);
 }
 
 void RemoveNodePreservingChildrenCommand::doApply()
 {
     Vector<RefPtr<Node> > children;
     for (Node* child = m_node->firstChild(); child; child = child->nextSibling())
         children.append(child);
 
     size_t size = children.size();
     for (size_t i = 0; i < size; ++i) {
         RefPtr<Node> child = children[i].release();
         removeNode(child, m_shouldAssumeContentIsAlwaysEditable);
         insertNodeBefore(child.release(), m_node, m_shouldAssumeContentIsAlwaysEditable);
     }
     removeNode(m_node, m_shouldAssumeContentIsAlwaysEditable);
 }
 
 }