<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
  <title>pseudo double SetInitialChildlist</title>
  <style>
   .cat::-moz-table-row-group { overflow: scroll;}
   tr { position: absolute;}
  </style>
 </head>

 <body>

  <table class="cat">
   <tr>
    <td>Cell</td>
   </tr>
  </table>

 </body>
</html>