<!DOCTYPE HTML>
<html class="reftest-wait">
<head>
<style>
#a {
  display: block;
  opacity:1;
  overflow:hidden;
  width: 100px;
  height: 100px;
  background-color: lime;
}
</style>
</head>
<body>
<span id="a"></span>
<script>
function doe() {
 document.getElementById('a').style.opacity = '0';
 document.documentElement.removeAttribute("class");
}
document.addEventListener("MozReftestInvalidate", doe, false);
</script>
</body>
</html>