<html>

<head>
<script>
function boom()
{
  var aaa = document.getElementById("aaa");
  var bbb = document.getElementById("bbb");
  aaa.parentNode.insertBefore(bbb, aaa);
}
</script>
</head>

<body onload="boom();">

<div><span><span style="display: table-caption;"></span><span id="aaa"><div></div></span></span></div>

<b id="bbb" style="display: table-caption;"></b>

</body>

</html>