Move Node::lastDescendantOrSelf() to NodeTraversal and rename to lastWithinOrSelf()

Source/core/editing/ReplaceSelectionCommand.h

Index: Source/core/editing/ReplaceSelectionCommand.h
diff --git a/Source/core/editing/ReplaceSelectionCommand.h b/Source/core/editing/ReplaceSelectionCommand.h
index fdd632ff895ef9785247cc217f29c13152e42b5f..e08f1ed770032287ea12508d5d653a328597da1a 100644
--- a/Source/core/editing/ReplaceSelectionCommand.h
+++ b/Source/core/editing/ReplaceSelectionCommand.h
@@ -69,8 +69,8 @@ private:
         void didReplaceNode(Node&, Node& newNode);
 
         Node* firstNodeInserted() const { return m_firstNodeInserted.get(); }
-        Node* lastLeafInserted() const { return m_lastNodeInserted ? &m_lastNodeInserted->lastDescendantOrSelf() : 0; }
-        Node* pastLastLeaf() const { return m_lastNodeInserted ? NodeTraversal::next(m_lastNodeInserted->lastDescendantOrSelf()) : 0; }
+        Node* lastLeafInserted() const { return m_lastNodeInserted ? &NodeTraversal::lastWithinOrSelf(*m_lastNodeInserted) : 0; }
+        Node* pastLastLeaf() const { return m_lastNodeInserted ? NodeTraversal::next(NodeTraversal::lastWithinOrSelf(*m_lastNodeInserted)) : 0; }
 
     private:
         RefPtrWillBeMember<Node> m_firstNodeInserted;