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

Source/core/svg/SVGAElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2010 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.
@@ skipping 161 matching lines @@
                 // Only allow navigation to internal <view> anchors.
                 if (targetElement && !targetElement->hasTagName(SVGNames::viewTag))
                     return;
             }
 
             String target = this->target();
             if (target.isEmpty() && fastGetAttribute(XLinkNames::showAttr) == "new")
                 target = "_blank";
             event->setDefaultHandled();
 
-            Frame* frame = document()->frame();
+            Frame* frame = document().frame();
             if (!frame)
                 return;
-            FrameLoadRequest frameRequest(document()->securityOrigin(), ResourceRequest(document()->completeURL(url)), target);
+            FrameLoadRequest frameRequest(document().securityOrigin(), ResourceRequest(document().completeURL(url)), target);
             frameRequest.setTriggeringEvent(event);
             frame->loader()->load(frameRequest);
             return;
         }
     }
 
     SVGGraphicsElement::defaultEventHandler(event);
 }
 
 bool SVGAElement::supportsFocus() const
@@ skipping 19 matching lines @@
 bool SVGAElement::isMouseFocusable() const
 {
     return false;
 }
 
 bool SVGAElement::isKeyboardFocusable() const
 {
     if (!isFocusable())
         return false;
 
-    if (Page* page = document()->page())
+    if (Page* page = document().page())
         return page->chrome().client().tabsToLinks();
     return false;
 }
 
 bool SVGAElement::childShouldCreateRenderer(const NodeRenderingContext& childContext) const
 {
     // http://www.w3.org/2003/01/REC-SVG11-20030114-errata#linking-text-environment
     // The 'a' element may contain any element that its parent may contain, except itself.
     if (childContext.node()->hasTagName(SVGNames::aTag))
         return false;
     if (parentNode() && parentNode()->isSVGElement())
         return parentNode()->childShouldCreateRenderer(childContext);
 
     return SVGElement::childShouldCreateRenderer(childContext);
 }
 
 } // namespace WebCore