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

Source/core/html/HTMLTemplateElement.cpp

 /*
  * Copyright (C) 2012 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 39 matching lines @@
 }
 
 PassRefPtr<HTMLTemplateElement> HTMLTemplateElement::create(const QualifiedName& tagName, Document* document)
 {
     return adoptRef(new HTMLTemplateElement(tagName, document));
 }
 
 DocumentFragment* HTMLTemplateElement::content() const
 {
     if (!m_content)
-        m_content = TemplateContentDocumentFragment::create(document()->ensureTemplateDocument(), this);
+        m_content = TemplateContentDocumentFragment::create(document().ensureTemplateDocument(), this);
 
     return m_content.get();
 }
 
 PassRefPtr<Node> HTMLTemplateElement::cloneNode(bool deep)
 {
     if (!deep)
         return cloneElementWithoutChildren();
 
     RefPtr<Node> clone = cloneElementWithChildren();
     if (m_content)
         content()->cloneChildNodes(toHTMLTemplateElement(clone.get())->content());
     return clone.release();
 }
 
 void HTMLTemplateElement::didMoveToNewDocument(Document* oldDocument)
 {
     HTMLElement::didMoveToNewDocument(oldDocument);
     if (!m_content)
         return;
-    document()->ensureTemplateDocument()->adoptIfNeeded(m_content.get());
+    document().ensureTemplateDocument()->adoptIfNeeded(m_content.get());
 }
 
 #ifndef NDEBUG
 const HTMLTemplateElement* toHTMLTemplateElement(const Node* node)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!node || (node->isHTMLElement() && node->hasTagName(templateTag)));
     return static_cast<const HTMLTemplateElement*>(node);
 }
 #endif
 
 } // namespace WebCore