<html class="reftest-wait">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  </head>
  <body onload="start()">
    <iframe src="data:text/html,<body contenteditable spellcheck=false>foo bar"></iframe>
    <script>
      function start() {
        var iframe = document.querySelector("iframe");
        var win = iframe.contentWindow;
        var doc = iframe.contentDocument;

        setTimeout(function() {
          doc.body.focus();

          // Now try to set the caret without moving it
          win.getSelection().collapse(doc.body.firstChild, 1);

          document.documentElement.removeAttribute("class");
        }, 0);
      }
    </script>
  </body>
</html>