<!DOCTYPE html>
<html>
<head>
<script>

function boom()
{
  var mo = document.createElementNS("http://www.w3.org/1998/Math/MathML", "mo");
  var t1 = document.createTextNode("123456 ");
  mo.appendChild(t1);
  document.body.appendChild(mo);
  var t2 = document.createTextNode("x");
  document.body.appendChild(t2);

  var r1 = document.createRange();
  r1.setEnd(t1, 7);
  var r3 = document.createRange();
  r3.setStart(t1, 7);

  document.documentElement.offsetHeight;

  t1.splitText(t1.length);
}

</script>
</head>

<body onload="boom();"></body>
</html>
