<!DOCTYPE html>
<html class="reftest-wait">
<head>
<style type="text/css">
#sibling1 {
 height: 20px;
 background-color: green;
 margin-bottom: 10px;
}
#sibling2 {
 height: 20px;
 background-color: green;
 margin-top: 20px;
 margin-bottom: 20px;
}
#sibling3 {
 height: 20px;
 background-color: green;
 margin-top: 20px;
}
</style>
<script type="text/javascript">
function test() {
 document.getElementById('sibling2').style.display = 'none';
 document.documentElement.removeAttribute('class');
}
document.addEventListener('MozReftestInvalidate', test);
</script>
</head>
<body>
<div id="sibling1"></div>
<div id="sibling2"></div>
<div id="sibling3"></div>
</body>
</html>