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

Source/core/dom/NodeIterator.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2000 Frederik Holljen (frederik.holljen@hig.no)
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2008 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
  * License as published by the Free Software Foundation; either
@@ skipping 61 matching lines @@
     node = NodeTraversal::previous(node.get(), root);
     return node;
 }
 
 NodeIterator::NodeIterator(PassRefPtr<Node> rootNode, unsigned whatToShow, PassRefPtr<NodeFilter> filter)
     : Traversal(rootNode, whatToShow, filter)
     , m_referenceNode(root(), true)
     , m_detached(false)
 {
     ScriptWrappable::init(this);
-    root()->document()->attachNodeIterator(this);
+    root()->document().attachNodeIterator(this);
 }
 
 NodeIterator::~NodeIterator()
 {
-    root()->document()->detachNodeIterator(this);
+    root()->document().detachNodeIterator(this);
 }
 
 PassRefPtr<Node> NodeIterator::nextNode(ScriptState* state, ExceptionState& es)
 {
     if (m_detached) {
         es.throwDOMException(InvalidStateError);
         return 0;
     }
 
     RefPtr<Node> result;
@@ skipping 42 matching lines @@
             break;
         }
     }
 
     m_candidateNode.clear();
     return result.release();
 }
 
 void NodeIterator::detach()
 {
-    root()->document()->detachNodeIterator(this);
+    root()->document().detachNodeIterator(this);
     m_detached = true;
     m_referenceNode.node.clear();
 }
 
 void NodeIterator::nodeWillBeRemoved(Node* removedNode)
 {
     updateForNodeRemoval(removedNode, m_candidateNode);
     updateForNodeRemoval(removedNode, m_referenceNode);
 }
 
 void NodeIterator::updateForNodeRemoval(Node* removedNode, NodePointer& referenceNode) const
 {
     ASSERT(!m_detached);
     ASSERT(removedNode);
-    ASSERT(root()->document());
-    ASSERT(root()->document() == removedNode->document());
+    ASSERT(&root()->document() == &removedNode->document());
 
     // Iterator is not affected if the removed node is the reference node and is the root.
     // or if removed node is not the reference node, or the ancestor of the reference node.
     if (!removedNode->isDescendantOf(root()))
         return;
     bool willRemoveReferenceNode = removedNode == referenceNode.node;
     bool willRemoveReferenceNodeAncestor = referenceNode.node && referenceNode.node->isDescendantOf(removedNode);
     if (!willRemoveReferenceNode && !willRemoveReferenceNodeAncestor)
         return;
 
@@ skipping 45 matching lines @@
                     node = NodeTraversal::previous(node, root());
             }
             if (node)
                 referenceNode.node = node;
         }
     }
 }
 
 
 } // namespace WebCore