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

function expStr(s, n)
{
  for (var i = 0; i < n; ++i)
    s += s;
  return s;
}

function boom()
{
  var s = document.getElementById("s")
  var t = document.createTextNode(expStr("x ", 15));
  s.appendChild(t);
  document.documentElement.offsetHeight;
  s.removeChild(t);
}
  
</script>
</head>

<body onload="boom();"><div style="width: 1px"><span id="s"></span></div></body>
</html>