Move highestAncestorOrSelf() from Node to NodeTraversal

Source/core/dom/ContainerNode.h

Index: Source/core/dom/ContainerNode.h
diff --git a/Source/core/dom/ContainerNode.h b/Source/core/dom/ContainerNode.h
index 198a191ae905a19a2e8f643e621e48fbe2b38342..e65fc4376a223d0bee5f2e7618a92ac04a30e0ad 100644
--- a/Source/core/dom/ContainerNode.h
+++ b/Source/core/dom/ContainerNode.h
@@ -295,15 +295,6 @@ inline Node* Node::lastChild() const
     return toContainerNode(this)->lastChild();
 }
 
-inline Node& Node::highestAncestorOrSelf() const
-{
-    Node* node = const_cast<Node*>(this);
-    Node* highest = node;
-    for (; node; node = node->parentNode())
-        highest = node;
-    return *highest;
-}
-
 inline ContainerNode* Node::parentElementOrShadowRoot() const
 {
     ContainerNode* parent = parentNode();