<style id="a">
.z {
  marker-mid: url(#blah);
  display: inline-table;
  contain: layout size;
}
</style>
<script>
function go() {
  f.width;
  a.appendChild(d);
}
</script>
<body onload="go()">
  <base href="x"></base>

  <div class="z">
    <img id="f">
    <datalist id="d"></datalist>
  </div>
</body>