The Tor Browser / file revision

 <?xml version="1.0"?>

 <?xml-stylesheet href="chrome://global/skin" type="text/css"?>

 <?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css"

                  type="text/css"?>

 <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

   <browser type="content"

            src="data:text/html,<script>var x = new XMLHttpRequest(); x.onreadystatechange = function() {}</script>"/>

   <script type="application/javascript"><![CDATA[

     window.onload = function() {

       var z = new XPCNativeWrapper(window.frames[0].wrappedJSObject.x).onreadystatechange;

       var t = window.opener.SimpleTest;

       t.ok(true, "Hey, we didn't crash");

       window.close();

       t.finish();

     }

     ]]>

 </script>

 </window>