Add toPluginDocument() convenience method that takes a reference in argument

Source/core/html/HTMLEmbedElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Stefan Schimanski (1Stein@gmx.de)
  * Copyright (C) 2004, 2005, 2006, 2008, 2009, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 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
@@ skipping 144 matching lines @@
     Vector<String> paramValues;
     parametersForPlugin(paramNames, paramValues);
 
     RefPtr<HTMLEmbedElement> protect(this); // Loading the plugin might remove us from the document.
     bool beforeLoadAllowedLoad = dispatchBeforeLoadEvent(m_url);
     if (!beforeLoadAllowedLoad) {
         if (document().isPluginDocument()) {
             // Plugins inside plugin documents load differently than other plugins. By the time
             // we are here in a plugin document, the load of the plugin (which is the plugin document's
             // main resource) has already started. We need to explicitly cancel the main resource load here.
-            toPluginDocument(&document())->cancelManualPluginLoad();
+            toPluginDocument(document()).cancelManualPluginLoad();
         }
         return;
     }
     if (!renderer()) // Do not load the plugin if beforeload removed this element or its renderer.
         return;
 
     // FIXME: beforeLoad could have detached the renderer!  Just like in the <object> case above.
     requestObject(m_url, m_serviceType, paramNames, paramValues);
 }
 
@@ skipping 30 matching lines @@
 }
 
 void HTMLEmbedElement::addSubresourceAttributeURLs(ListHashSet<KURL>& urls) const
 {
     HTMLPlugInImageElement::addSubresourceAttributeURLs(urls);
 
     addSubresourceURL(urls, document().completeURL(getAttribute(srcAttr)));
 }
 
 }