<!DOCTYPE html>
<html style="font-family: Ahem; font-size: 50px; -webkit-font-smoothing: none;">
<body>
<script>
document.body.offsetTop;
test = document.createElement('div');
document.body.appendChild(test)
test.appendChild(document.createElement('td'));
td = document.createElement('td');
test.appendChild(td);
document.body.offsetTop;
test.insertBefore(document.createElement('div'), td);
</script>
</body>
</html>