Have Element::ensureUserAgentShadowRoot() return a reference

Source/core/html/HTMLSummaryElement.cpp

 /*
  * Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 35 matching lines @@
     : HTMLElement(tagName, document)
 {
     ASSERT(hasTagName(summaryTag));
 }
 
 RenderObject* HTMLSummaryElement::createRenderer(RenderStyle*)
 {
     return new RenderBlockFlow(this);
 }
 
-void HTMLSummaryElement::didAddUserAgentShadowRoot(ShadowRoot* root)
+void HTMLSummaryElement::didAddUserAgentShadowRoot(ShadowRoot& root)
 {
-    root->appendChild(DetailsMarkerControl::create(document()));
-    root->appendChild(HTMLContentElement::create(document()));
+    root.appendChild(DetailsMarkerControl::create(document()));
+    root.appendChild(HTMLContentElement::create(document()));
 }
 
 HTMLDetailsElement* HTMLSummaryElement::detailsElement() const
 {
     Node* parent = NodeRenderingTraversal::parent(this);
     if (parent && isHTMLDetailsElement(parent))
         return toHTMLDetailsElement(parent);
     return 0;
 }
 
@@ skipping 63 matching lines @@
 
 bool HTMLSummaryElement::willRespondToMouseClickEvents()
 {
     if (isMainSummary() && renderer())
         return true;
 
     return HTMLElement::willRespondToMouseClickEvents();
 }
 
 }