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

Source/core/svg/SVGStyleElement.h

 /*
  * Copyright (C) 2004, 2005 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  *
  * 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,
@@ skipping 42 matching lines @@
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
     virtual InsertionNotificationRequest insertedInto(ContainerNode*) OVERRIDE;
     virtual void didNotifySubtreeInsertions(ContainerNode*) OVERRIDE;
     virtual void removedFrom(ContainerNode*) OVERRIDE;
     virtual void childrenChanged(bool changedByParser = false, Node* beforeChange = 0, Node* afterChange = 0, int childCountDelta = 0);
 
     virtual void finishParsingChildren();
     virtual bool rendererIsNeeded(const NodeRenderingContext&) OVERRIDE { return false; }
 
     virtual bool isLoading() const { return StyleElement::isLoading(); }
-    virtual bool sheetLoaded() { return StyleElement::sheetLoaded(document()); }
-    virtual void startLoadingDynamicSheet() { StyleElement::startLoadingDynamicSheet(document()); }
+    virtual bool sheetLoaded() { return StyleElement::sheetLoaded(&document()); }
+    virtual void startLoadingDynamicSheet() { StyleElement::startLoadingDynamicSheet(&document()); }
     virtual Timer<SVGElement>* svgLoadEventTimer() OVERRIDE { return &m_svgLoadEventTimer; }
 
     Timer<SVGElement> m_svgLoadEventTimer;
 };
 
 } // namespace WebCore
 
 #endif // SVGStyleElement_h