Make sure the rootNode of a LiveNodeListBase is always a ContainerNode

Source/core/dom/NodeList.h

Index: Source/core/dom/NodeList.h
diff --git a/Source/core/dom/NodeList.h b/Source/core/dom/NodeList.h
index 8dfd010b27d3abc334c416ffec9a778dc231c860..66072472d583ef0ff6cf782f117eed7b5044b01e 100644
--- a/Source/core/dom/NodeList.h
+++ b/Source/core/dom/NodeList.h
@@ -43,6 +43,9 @@ public:
 
     // Other methods (not part of DOM)
     virtual bool isLiveNodeList() const { return false; }
+    virtual bool isEmptyNodeList() const { return false; }
+    virtual bool isChildNodeList() const { return false; }
+
     void anonymousNamedGetter(const AtomicString&, bool&, RefPtr<Node>&, bool&, unsigned&);
     Node* ownerNode() const;