<html><head>
<title>Crash [@ nsGenericElement::SetAttr] with classList.toggle</title>
<script>
var classList;
var interval;
function run() {
  classList = window.frames[0].document.documentElement.classList;
  window.frames[0].location.reload();
  interval = setInterval(function(aClassList) {aClassList.toggle('a'); forcegc();}, 10, classList);
  // Let the interval run for awhile and close the window after 2 seconds.
  setTimeout(function() { clearInterval(interval); window.opener.done(); window.close(); }, 2000);
}

function forcegc(){
  SpecialPowers.forceGC();
  SpecialPowers.gc();
}

    </script>
  </head>
  <body onload="run()">
    <iframe></iframe>
  </body>
</html>

