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

Source/core/html/HTMLPlugInImageElement.cpp

 /*
  * Copyright (C) 2008, 2011, 2012 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
  * 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 242 matching lines @@
 
     // FIXME: This code should not depend on renderer!
     if (!renderer || useFallback)
         return false;
 
     LOG(Plugins, "%p Plug-in URL: %s", this, m_url.utf8().data());
     LOG(Plugins, "   Loaded URL: %s", url.string().utf8().data());
     m_loadedUrl = url;
 
     IntSize contentSize = roundedIntSize(LayoutSize(renderer->contentWidth(), renderer->contentHeight()));
-    bool loadManually = document().isPluginDocument() && !frame->loader()->containsPlugins() && toPluginDocument(&document())->shouldLoadPluginManually();
+    bool loadManually = document().isPluginDocument() && !frame->loader()->containsPlugins() && toPluginDocument(document()).shouldLoadPluginManually();
     RefPtr<Widget> widget = frame->loader()->client()->createPlugin(contentSize, this, url, paramNames, paramValues, mimeType, loadManually);
 
     if (!widget) {
         if (!renderer->showsUnavailablePluginIndicator())
             renderer->setPluginUnavailabilityReason(RenderEmbeddedObject::PluginMissing);
         return false;
     }
 
     renderer->setWidget(widget);
     frame->loader()->setContainsPlugins();
@@ skipping 48 matching lines @@
         renderEmbeddedObject()->setPluginUnavailabilityReason(RenderEmbeddedObject::PluginBlockedByContentSecurityPolicy);
         return false;
     }
 
     if (frame->loader() && !frame->loader()->mixedContentChecker()->canRunInsecureContent(document().securityOrigin(), url))
         return false;
     return true;
 }
 
 } // namespace WebCore