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

Source/core/dom/EventRetargeter.cpp

 /*
  * Copyright (C) 2013 Google 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 29 matching lines @@
 
 static inline bool inTheSameScope(ShadowRoot* shadowRoot, EventTarget* target)
 {
     return target->toNode() && target->toNode()->treeScope()->rootNode() == shadowRoot;
 }
 
 static inline EventDispatchBehavior determineDispatchBehavior(Event* event, ShadowRoot* shadowRoot, EventTarget* target)
 {
     // Video-only full screen is a mode where we use the shadow DOM as an implementation
     // detail that should not be detectable by the web content.
-    if (Element* element = FullscreenElementStack::currentFullScreenElementFrom(target->toNode()->document())) {
+    if (Element* element = FullscreenElementStack::currentFullScreenElementFrom(&target->toNode()->document())) {
         // FIXME: We assume that if the full screen element is a media element that it's
         // the video-only full screen. Both here and elsewhere. But that is probably wrong.
         if (element->isMediaElement() && shadowRoot && shadowRoot->host() == element)
             return StayInsideShadowDOM;
     }
 
     // WebKit never allowed selectstart event to cross the the shadow DOM boundary.
     // Changing this breaks existing sites.
     // See https://bugs.webkit.org/show_bug.cgi?id=52195 for details.
     const AtomicString eventType = event->type();
@@ skipping 211 matching lines @@
             break;
         }
         scope = scope->parentTreeScope();
     }
     for (Vector<TreeScope*, 32>::iterator iter = parentTreeScopes.begin(); iter < parentTreeScopes.end(); ++iter)
         relatedNodeMap.add(*iter, relatedNode);
     return relatedNode;
 }
 
 }