<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" onload="runTest()">
  <path id="bar" d="M150 50 L 450 50" />
  <text>
    <textPath id="theTP" xlink:href="#foo">PASS</textPath>
  </text>
  <script><![CDATA[
    function runTest() {
      var path = document.getElementById("bar");
      path.setAttribute("id","foo");
    }
  ]]></script>
</svg>