Stop about:tracing from dropping child slices of didNotFinish slices.

chrome/browser/resources/tracing/test_utils.js

 // Copyright (c) 2011 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.
 
 /**
  * @fileoverview Helper functions for use in tracing tests.
  */
 cr.define('test_utils', function() {
   function getJSON(url, cb) {
     var req = new XMLHttpRequest();
@@ skipping 11 matching lines @@
             console.log('Failed to load ' + url);
           }
         }, 0);
       }
     };
     req.send(null);
   }
   return {
     getJSON: getJSON
   };
-});
+});