Remove dead code from LiveNodeListBase

Source/core/dom/LiveNodeList.cpp

 /*
  * 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, 2008, 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 31 matching lines @@
         return 0;
     return toContainerNode(&rootNode);
 }
 
 void LiveNodeListBase::invalidateCache() const
 {
     m_cachedItem = 0;
     m_isLengthCacheValid = false;
     m_isItemCacheValid = false;
     m_isNameCacheValid = false;
-    m_isItemRefElementsCacheValid = false;
     if (isNodeList(type()))
         return;
 
     const HTMLCollection* cacheBase = static_cast<const HTMLCollection*>(this);
     cacheBase->m_idCache.clear();
     cacheBase->m_nameCache.clear();
     cacheBase->m_cachedElementsArrayOffset = 0;
 }
 
 void LiveNodeListBase::invalidateIdNameCacheMaps() const
@@ skipping 22 matching lines @@
         Node* node = item(i);
         // FIXME: This should probably be using getIdAttribute instead of idForStyleResolution.
         if (node->hasID() && toElement(node)->idForStyleResolution() == elementId)
             return node;
     }
 
     return 0;
 }
 
 } // namespace WebCore