The Tor Browser / file revision

 <?xml version="1.0"?>

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

 <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="boom();" class="reftest-wait">

 <script type="text/javascript">

 // <![CDATA[

 var HTML_NS   = "http://www.w3.org/1999/xhtml";

 var MATHML_NS = "http://www.w3.org/1998/Math/MathML";

 var XUL_NS    = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";

 function boom()

 {

     var listbox = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "listbox");

     var listitem = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "listitem");

     listbox.appendChild(listitem);

     document.documentElement.appendChild(listbox);

     var hbox = document.createElementNS(XUL_NS, "hbox");

     listbox.appendChild(hbox);

     var mphantom = document.createElementNS(MATHML_NS, 'mphantom');

     listbox.appendChild(mphantom);

     var wax = document.createElementNS(MATHML_NS, 'wax');

     hbox.appendChild(wax);

     var msub = document.createElementNS(MATHML_NS, 'msub');

     wax.appendChild(msub);

     var merror = document.createElementNS(MATHML_NS, 'merror');

     wax.appendChild(merror);

     var span = document.createElementNS(HTML_NS, 'span');

     mphantom.appendChild(span);

     var vbox = document.createElementNS(XUL_NS, 'vbox');

     span.appendChild(vbox);

     setTimeout(boom2, 0);

     function boom2()

     {

         var munderover = document.createElementNS(MATHML_NS, 'munderover'); 

         msub.appendChild(munderover);

         var mtext = document.createElementNS(MATHML_NS, 'mtext');

         span.appendChild(mtext);

         document.documentElement.removeAttribute("class");

     }

 }

 // ]]>

 </script>

 </window>