Have StyleSheetCollections constructor take a Document reference in argument

Source/core/dom/StyleSheetCollection.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 50 matching lines @@
     const Vector<RefPtr<CSSStyleSheet> >& activeAuthorStyleSheets() const { return m_activeAuthorStyleSheets; }
     const Vector<RefPtr<StyleSheet> >& styleSheetsForStyleSheetList() const { return m_styleSheetsForStyleSheetList; }
 
     bool usesRemUnits() const { return m_usesRemUnits; }
 
     DocumentOrderedList& styleSheetCandidateNodes() { return m_styleSheetCandidateNodes; }
     DocumentOrderedList* scopingNodesForStyleScoped() { return m_scopingNodesForStyleScoped.scopingNodes(); }
     ListHashSet<Node*, 4>* scopingNodesRemoved() { return m_scopingNodesForStyleScoped.scopingNodesRemoved(); }
 
 protected:
-    explicit StyleSheetCollection(TreeScope*);
+    explicit StyleSheetCollection(TreeScope&);
 
-    Document* document() { return m_treeScope->documentScope(); }
+    Document* document() { return m_treeScope.documentScope(); }
 
     enum StyleResolverUpdateType {
         Reconstruct,
         Reset,
         Additive
     };
     void analyzeStyleSheetChange(StyleResolverUpdateMode, const Vector<RefPtr<CSSStyleSheet> >& oldStyleSheets, const Vector<RefPtr<CSSStyleSheet> >& newStylesheets, StyleResolverUpdateType&, bool& requiresFullStyleRecalc);
     void resetAllRuleSetsInTreeScope(StyleResolver*);
     void updateUsesRemUnits();
 
 private:
     StyleResolverUpdateType compareStyleSheets(const Vector<RefPtr<CSSStyleSheet> >& oldStyleSheets, const Vector<RefPtr<CSSStyleSheet> >& newStylesheets, Vector<StyleSheetContents*>& addedSheets);
     bool activeLoadingStyleSheetLoaded(const Vector<RefPtr<CSSStyleSheet> >& newStyleSheets);
 
 protected:
     Vector<RefPtr<StyleSheet> > m_styleSheetsForStyleSheetList;
     Vector<RefPtr<CSSStyleSheet> > m_activeAuthorStyleSheets;
 
-    TreeScope* m_treeScope;
+    TreeScope& m_treeScope;
     bool m_hadActiveLoadingStylesheet;
     bool m_usesRemUnits;
 
     DocumentOrderedList m_styleSheetCandidateNodes;
     StyleSheetScopingNodeList m_scopingNodesForStyleScoped;
 };
 
 }
 
 #endif