Fix race-condition in ct-embedded-flakiness-dashboard-tests.

Tools/GardeningServer/ui/ct-embedded-flakiness-dashboard.html

 <!--
 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.
 -->
 
 <polymer-element name="ct-embedded-flakiness-dashboard" attributes="test">
   <template>
     <style>
       :host {
@@ skipping 14 matching lines @@
         window.addEventListener('message', function(event) {
           if (event.data.command != 'heightChanged')
             return;
 
           this.$.iframe.style.height = event.data.height + 'px';
         }.bind(this));
       },
 
       testChanged: function() {
         this.$.iframe.src = ui.urlForEmbeddedFlakinessDashboard([this.test]);
-      },      
+      },
 
     });
   </script>
 </polymer-element>