Have Element::ensureUserAgentShadowRoot() return a reference

Source/core/html/HTMLInputElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2012 Samsung Electronics. All rights reserved.
@@ skipping 123 matching lines @@
     return inputElement.release();
 }
 
 HTMLImageLoader* HTMLInputElement::imageLoader()
 {
     if (!m_imageLoader)
         m_imageLoader = adoptPtr(new HTMLImageLoader(this));
     return m_imageLoader.get();
 }
 
-void HTMLInputElement::didAddUserAgentShadowRoot(ShadowRoot*)
+void HTMLInputElement::didAddUserAgentShadowRoot(ShadowRoot&)
 {
     m_inputType->createShadowSubtree();
 }
 
 void HTMLInputElement::didAddShadowRoot(ShadowRoot& root)
 {
     if (!root.isOldestAuthorShadowRoot())
         return;
     m_inputTypeView = InputTypeView::create(*this);
 }
@@ skipping 1704 matching lines @@
 }
 
 #if ENABLE(INPUT_MULTIPLE_FIELDS_UI)
 PassRefPtr<RenderStyle> HTMLInputElement::customStyleForRenderer()
 {
     return m_inputTypeView->customStyleForRenderer(originalStyleForRenderer());
 }
 #endif
 
 } // namespace