<!DOCTYPE html>
<html>
<body>
PASS if no crash.
<table>
  <tbody>
    <tr id="tr_first_table"></tr>
  </tbody>
  <tbody>
   <tr>
     <th>2</th>
     <th id="th_first_table">3</th>
  </tr>
  </tbody>
</table>
<br>
<table>
  <th id="th_second_table">4</th>
  <th rowspan="6" id="th_withh_rowspan">5</th>
</table>
<script>
if (window.testRunner)
    testRunner.dumpAsText();
  
document.body.offsetHeight;
th_second_table.appendChild(th_first_table);
document.body.offsetHeight;
tr_first_table.appendChild(th_withh_rowspan);
document.body.offsetHeight;
</script>
</body>
</html>