Implement Node.treeRoot

third_party/WebKit/Source/core/dom/Node.cpp

Index: third_party/WebKit/Source/core/dom/Node.cpp
diff --git a/third_party/WebKit/Source/core/dom/Node.cpp b/third_party/WebKit/Source/core/dom/Node.cpp
index 405626d58eee2af4fcfb56cc1c1df90f662223e0..404c3510122d9af8d674d5bc1c396dea30873d21 100644
--- a/third_party/WebKit/Source/core/dom/Node.cpp
+++ b/third_party/WebKit/Source/core/dom/Node.cpp
@@ -450,6 +450,15 @@ Node* Node::pseudoAwareLastChild() const
     return lastChild();
 }
 
+Node* Node::treeRoot()
+{
+    Node* node = this;
+    while (!isTreeScopeRoot(node)) {

[kochi, 2016/01/27 09:18:50]

style nit: if the loop body is one-liner, you have to omit enclosing {}.

(probably fixed code doesn't have one-line body though.)

[kochi, 2016/01/27 09:18:50]

You can get its treeroot by treeScope().rootNode() in O(1) time, and
that is why we want this API exposed to JavaScript, otherwise JavaScript
code can do the same but in O(depth) time.

[yuzuchan, 2016/01/28 06:23:56]

Done.

[yuzuchan, 2016/01/28 06:23:56]

Done.

+        node = node->parentNode();

[kochi, 2016/01/27 09:18:50]

This doesn't work for detached tree (i.e. not in document
or shadow root).

If node->parentNode() returns null, you should return the node
as treeRoot, but this code goes to next iteration and exits the
loop in !isTreeScopeRoot() check (which checks !node) with node == nullptr.

[yuzuchan, 2016/01/28 06:23:56]

Done.

+    }
+    return node;
+}
+
 PassRefPtrWillBeRawPtr<Node> Node::insertBefore(PassRefPtrWillBeRawPtr<Node> newChild, Node* refChild, ExceptionState& exceptionState)
 {
     if (isContainerNode())