Make HTMLCollection / NodeList backward traversal consistent with forward one

Source/core/dom/LiveNodeList.cpp

Index: Source/core/dom/LiveNodeList.cpp
diff --git a/Source/core/dom/LiveNodeList.cpp b/Source/core/dom/LiveNodeList.cpp
index 25ea0915f19e03593d60fc9f9ea81c494e77d90d..7425e9cbf99404b4ed3f77ba930571e578d62d78 100644
--- a/Source/core/dom/LiveNodeList.cpp
+++ b/Source/core/dom/LiveNodeList.cpp
@@ -40,14 +40,14 @@ void LiveNodeList::invalidateCache(Document*) const
     m_collectionIndexCache.invalidate();
 }
 
-Element* LiveNodeList::itemBefore(const Element* previous) const
+Element* LiveNodeList::traverseToFirstElement() const
 {
-    return LiveNodeListBase::itemBefore(*this, previous);
+    return firstMatchingElement(*this);
 }
 
-Element* LiveNodeList::traverseToFirstElement() const
+Element* LiveNodeList::traverseToLastElement() const
 {
-    return firstMatchingElement(*this);
+    return lastMatchingElement(*this);
 }
 
 Element* LiveNodeList::traverseForwardToOffset(unsigned offset, Element& currentNode, unsigned& currentOffset) const
@@ -55,4 +55,9 @@ Element* LiveNodeList::traverseForwardToOffset(unsigned offset, Element& current
     return traverseMatchingElementsForwardToOffset(*this, offset, currentNode, currentOffset);
 }
 
+Element* LiveNodeList::traverseBackwardToOffset(unsigned offset, Element& currentNode, unsigned& currentOffset) const
+{
+    return traverseMatchingElementsBackwardToOffset(*this, offset, currentNode, currentOffset);
+}
+
 } // namespace WebCore