<!DOCTYPE html>
<html class="reftest-wait">
<head>
<body style="white-space:pre"> FG 
 JK 
<script>
document.body.offsetTop;
var t = document.body.firstChild;
var sel = window.getSelection();
sel.collapse(t, 1);
sel.extend(t, 3);

function doTest() {
  t.insertData(0, ' BC \n');
  document.documentElement.removeAttribute('class');
}
document.addEventListener("MozReftestInvalidate", doTest);
</script>
</body>
</html>