Fix broken parent->child link in automation webView.

chrome/renderer/resources/extensions/automation/automation_node.js

Index: chrome/renderer/resources/extensions/automation/automation_node.js
diff --git a/chrome/renderer/resources/extensions/automation/automation_node.js b/chrome/renderer/resources/extensions/automation/automation_node.js
index b13569d4c14f18d4bd72c25ffad1ed7b7207de44..728dc28255f3ca7d09ff284c3dbbf5d1cf3dad11 100644
--- a/chrome/renderer/resources/extensions/automation/automation_node.js
+++ b/chrome/renderer/resources/extensions/automation/automation_node.js
@@ -241,10 +241,12 @@ AutomationNodeImpl.prototype = {
     return GetIndexInParent(this.treeID, this.id);
   },
 
+  set childTree(node) {
+    this.childTree_ = node;
+  },
+
   get childTree() {
-    var childTreeID = GetIntAttribute(this.treeID, this.id, 'childTreeId');
-    if (childTreeID)
-      return AutomationRootNodeImpl.get(childTreeID);
+    return this.childTree_;
   },
 
   get firstChild() {