<html xmlns="http://www.w3.org/1999/xhtml">

<head>
  <title>Gracefully handle setting a field on a bad |this|</title>

  <bindings xmlns="http://www.mozilla.org/xbl">
    <binding id="a">
      <implementation>
        <field name="f">17</field>
      </implementation>
    </binding>
  </bindings>

  <script type="application/javascript">
    window.onload = function()
    {
      var bound = document.getElementById("bound");
      try
      {
        Object.getPrototypeOf(bound).f = 42;
      }
      catch (e) { /* Throwing's fine, crashing isn't. */ }
    };
  </script>
</head>

<body>
  <div id="bound" style="-moz-binding: url(#a)"></div>
</body>

</html>