Have LiveNodeListBase::ownerNode() return a reference

Source/core/dom/LiveNodeListBase.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. 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
@@ skipping 49 matching lines @@
         document().unregisterNodeList(this);
     }
 
     ContainerNode& rootNode() const;
 
     void didMoveToDocument(Document& oldDocument, Document& newDocument);
     ALWAYS_INLINE bool hasIdNameCache() const { return !isLiveNodeListType(type()); }
     ALWAYS_INLINE bool isRootedAtDocument() const { return m_rootType == NodeListIsRootedAtDocument; }
     ALWAYS_INLINE NodeListInvalidationType invalidationType() const { return static_cast<NodeListInvalidationType>(m_invalidationType); }
     ALWAYS_INLINE CollectionType type() const { return static_cast<CollectionType>(m_collectionType); }
-    ContainerNode* ownerNode() const { return m_ownerNode.get(); }
+    ContainerNode& ownerNode() const { return *m_ownerNode; }
     ALWAYS_INLINE void invalidateCache(const QualifiedName* attrName) const
     {
         if (!attrName || shouldInvalidateTypeOnAttributeChange(invalidationType(), *attrName))
             invalidateCache();
         else if (hasIdNameCache() && (*attrName == HTMLNames::idAttr || *attrName == HTMLNames::nameAttr))
             invalidateIdNameCacheMaps();
     }
     virtual void invalidateCache(Document* oldDocument = 0) const = 0;
 
     static bool shouldInvalidateTypeOnAttributeChange(NodeListInvalidationType, const QualifiedName&);
@@ skipping 82 matching lines @@
         current = previousNode(collection.rootNode(), *previous, collection.shouldOnlyIncludeDirectChildren());
     else
         current = lastNode(collection.rootNode(), collection.shouldOnlyIncludeDirectChildren());
 
     return iterateForPreviousNode(collection, current);
 }
 
 } // namespace WebCore
 
 #endif // LiveNodeListBase_h