<!DOCTYPE html>
<body>
<script>
  // Create the stylesheet via script, so that the parser's preloading doesn't
  // make the CSS loader hold on to the sheet we're _not_ trying to form a
  // cycle through, thus accidentally avoiding the cycle
  var link = document.createElement("link");
  link.setAttribute("rel", "stylesheet");
  link.setAttribute("href", "data:text/css,div { }");
  link.onload = function () {
    document.styleSheets[0].cssRules[0].style.foo = document;
  }
  document.body.appendChild(link);
</script>
