Completely detach removed nodes.

chrome/test/data/extensions/api_test/automation/tests/tabs/close_tab.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 var allTests = [
   function testCloseTab() {
     getUrlFromConfig('index.html', function(url) {
       chrome.tabs.create({'url': url}, function(tab) {
         chrome.automation.getTree(function(rootNode) {
+          var button = rootNode.find({role: 'button'});
+          assertEq(rootNode, button.root);
+
           rootNode.addEventListener(EventType.destroyed, function() {
             // Poll until the root node doesn't have a role anymore
             // indicating that it really did get cleaned up.
             function checkSuccess() {
-              if (rootNode.role === undefined)
+              if (rootNode.role === undefined && rootNode.root === null) {
+                assertEq(null, button.root);
                 chrome.test.succeed();
+              }
               else
                 window.setTimeout(checkSuccess, 10);
             }
             checkSuccess();
           });
           chrome.tabs.remove(tab.id);
         });
       });
     });
   }
 ]
 chrome.test.runTests(allTests);