The Tor Browser / file revision

 <title>iframe for between tests</title>

 <!--

   This page exists so that our accounting for assertions correctly

   counts assertions that happen while leaving a page.  We load this page

   after a test finishes, check the assertion counts, and then go on to

   load the next.

 -->

 <script>

 window.addEventListener("load", function() {

   var runner = (parent.TestRunner || parent.wrappedJSObject.TestRunner);

   runner.testUnloaded();

   if (SpecialPowers) {

     SpecialPowers.DOMWindowUtils.runNextCollectorTimer();

   }

 });

 </script>