<!DOCTYPE html>
<svg>
  <defs>
    <rect id="rect" width="50" height="100" fill="green"/>
  </defs>
  <use id="inner" href="#rect"/>
  <use href="#inner" x="50"/>
</svg>
<script>
onload = function() {
  // Make sure the shadow tree have been instantiated.
  document.body.offsetTop;

  let inner = document.querySelector('#inner');
  inner.setAttribute('href', location.href + '#rect');
};
</script>