Remove redundant m_isItemCacheValid flag from LiveNodeListBase

Source/core/dom/LiveNodeList.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.
  *
  * 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 35 matching lines @@
     enum ItemAfterOverrideType {
         OverridesItemAfter,
         DoesNotOverrideItemAfter,
     };
 
     LiveNodeListBase(Node* ownerNode, NodeListRootType rootType, NodeListInvalidationType invalidationType,
         bool shouldOnlyIncludeDirectChildren, CollectionType collectionType, ItemAfterOverrideType itemAfterOverrideType)
         : m_ownerNode(ownerNode)
         , m_cachedItem(0)
         , m_isLengthCacheValid(false)
-        , m_isItemCacheValid(false)
         , m_rootType(rootType)
         , m_invalidationType(invalidationType)
         , m_shouldOnlyIncludeDirectChildren(shouldOnlyIncludeDirectChildren)
         , m_collectionType(collectionType)
         , m_overridesItemAfter(itemAfterOverrideType == OverridesItemAfter)
     {
         ASSERT(m_rootType == static_cast<unsigned>(rootType));
         ASSERT(m_invalidationType == static_cast<unsigned>(invalidationType));
         ASSERT(m_collectionType == static_cast<unsigned>(collectionType));
         ASSERT(!m_overridesItemAfter || !isLiveNodeListType(collectionType));
@@ skipping 26 matching lines @@
     virtual void invalidateCache() const;
 
     static bool shouldInvalidateTypeOnAttributeChange(NodeListInvalidationType, const QualifiedName&);
 
 protected:
     Document& document() const { return m_ownerNode->document(); }
     Node& rootNode() const;
     ContainerNode* rootContainerNode() const;
     bool overridesItemAfter() const { return m_overridesItemAfter; }
 
-    ALWAYS_INLINE bool isItemCacheValid() const { return m_isItemCacheValid; }
     ALWAYS_INLINE Node* cachedItem() const { return m_cachedItem; }
-    ALWAYS_INLINE unsigned cachedItemOffset() const { return m_cachedItemOffset; }
+    ALWAYS_INLINE unsigned cachedItemOffset() const { ASSERT(cachedItem()); return m_cachedItemOffset; }
 
     ALWAYS_INLINE bool isLengthCacheValid() const { return m_isLengthCacheValid; }
     ALWAYS_INLINE unsigned cachedLength() const { return m_cachedLength; }
     ALWAYS_INLINE void setLengthCache(unsigned length) const
     {
         m_cachedLength = length;
         m_isLengthCacheValid = true;
     }
     ALWAYS_INLINE void setItemCache(Node* item, unsigned offset) const
     {
         ASSERT(item);
         m_cachedItem = item;
         m_cachedItemOffset = offset;
-        m_isItemCacheValid = true;
     }
 
     ALWAYS_INLINE NodeListRootType rootType() const { return static_cast<NodeListRootType>(m_rootType); }
     bool shouldOnlyIncludeDirectChildren() const { return m_shouldOnlyIncludeDirectChildren; }
 
 private:
     Node* itemBeforeOrAfterCachedItem(unsigned offset, ContainerNode* root) const;
     bool isLastItemCloserThanLastOrCachedItem(unsigned offset) const;
     bool isFirstItemCloserThanCachedItem(unsigned offset) const;
     Node* iterateForPreviousNode(Node* current) const;
     Node* itemBefore(Node* previousItem) const;
     void invalidateIdNameCacheMaps() const;
 
     RefPtr<Node> m_ownerNode;
     mutable Node* m_cachedItem;
     mutable unsigned m_cachedLength;
     mutable unsigned m_cachedItemOffset;
     mutable unsigned m_isLengthCacheValid : 1;
-    mutable unsigned m_isItemCacheValid : 1;
     const unsigned m_rootType : 2;
     const unsigned m_invalidationType : 4;
     const unsigned m_shouldOnlyIncludeDirectChildren : 1;
     const unsigned m_collectionType : 5;
 
     // From HTMLCollection
     const unsigned m_overridesItemAfter : 1;
 };
 
 ALWAYS_INLINE bool LiveNodeListBase::shouldInvalidateTypeOnAttributeChange(NodeListInvalidationType type, const QualifiedName& attrName)
@@ skipping 38 matching lines @@
     Node* traverseToFirstElement(ContainerNode& root) const;
     Node* traverseForwardToOffset(unsigned offset, Node& currentNode, unsigned& currentOffset, ContainerNode* root) const;
 
 private:
     virtual bool isLiveNodeList() const OVERRIDE FINAL { return true; }
 };
 
 } // namespace WebCore
 
 #endif // LiveNodeList_h