<!DOCTYPE html>
<html>
  <head>
    <style>
    body {
      margin: 0px;
    }

    iframe {
      position: absolute;
      width: 200px;
      height: 200px;
      border: none;
    }
    </style>
  </head>
  <body>
    <iframe src="/cross-site/bar.com/page_with_click_handler.html" style="opacity: 0;"></iframe>
    <div id="output">
    </div>
  </body>
</html>