gecko-dev/layout/generic/crashtests/1416544.html

<!DOCTYPE html>
<html>
<head>
  <style>

  body {
    columns: 2;
    -webkit-columns: 2;
  }
  span {
    float: right;
  }

  </style>
</head>
<body>

 <div>
      a
      <span>1</span>
 </div>

 <div>
    <div>
      b
      <span>2</span>
      <div></div>
    </div>
 </div>

</body>
</html>