Have ContainerNodeAlgorithms deal with references instead of pointers

Source/core/dom/shadow/ElementShadow.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 33 matching lines @@
     WTF_MAKE_NONCOPYABLE(ElementShadow); WTF_MAKE_FAST_ALLOCATED;
 public:
     static PassOwnPtr<ElementShadow> create();
     ~ElementShadow();
 
     Element* host() const;
     ShadowRoot* youngestShadowRoot() const { return m_shadowRoots.head(); }
     ShadowRoot* oldestShadowRoot() const { return m_shadowRoots.tail(); }
     ElementShadow* containingShadow() const;
 
-    ShadowRoot* addShadowRoot(Element* shadowHost, ShadowRoot::ShadowRootType);
+    ShadowRoot* addShadowRoot(Element& shadowHost, ShadowRoot::ShadowRootType);
 
     bool applyAuthorStyles() const { return m_applyAuthorStyles; }
     bool didAffectApplyAuthorStyles();
     bool containsActiveStyles() const;
 
     void attach(const Node::AttachContext&);
     void detach(const Node::AttachContext&);
 
     void removeAllEventListeners();
 
@@ skipping 65 matching lines @@
         return 0;
     if (Node* parent = node->parentNode())
         if (parent->isElementNode())
             return toElement(parent)->shadow();
     return 0;
 }
 
 } // namespace
 
 #endif