chromium/third_party/blink/manual_tests/inspector-wrappers/inspector-treeElementIdentifier.html

<html>
<head>
<script src="inspector-wrappers-test-utils.js"></script>
</head>
<body>
<script>
  document.body.__defineGetter__("__treeElementIdentifier", function() {
    try { doAttack(); } catch(ex) { }
    return this.___treeElementIdentifier;
  });
  document.body.__defineSetter__("__treeElementIdentifier", function(val) {
    this.___treeElementIdentifier = val;
  });
</script>
<script>instructions({trigger: "Collapse and expand the &lt;body/&gt; tag"});</script>
</body>
</html>