<html><body>
  Popup 2
  <script type="application/javascript">
    var bc = new BroadcastChannel("bug646641_2");
    window.onload = () => {
      bc.postMessage({ message: "childLoad", num: 2 })
      requestAnimationFrame(() => bc.postMessage({message: "childPageshow", num: 2}));
    }
    bc.onmessage = (msgEvent) => {
      var msg = msgEvent.data;
      if (msg == "go-2") {
        history.go(-2);
        bc.close();
      }
    }
  </script>
</body></html>