<!DOCTYPE html>
<html class="reftest-wait">
  <head>
    <script>
      window.addEventListener("MozReftestInvalidate",
        function() {
          var b = document.createElement("body");
          b.style.background = "green";
          document.documentElement.appendChild(b);
          document.documentElement.className = "";
        }, false);
    </script>
  </head>
  <body style="background: red">
    <script>
      document.documentElement.removeChild(document.body);
    </script>
  </body>
</html>