ocumentPosition($('#para-empty')));
</script>

<script id=proto>
  testing.expectEqual('HTMLDocument', content.getRootNode().__proto__.constructor.name);
</script>

<script id=firstChild>
  let body_first_child = document.body.firstChild;
  testing.expectEqual('div', body_first_child.localName);
  testing.expectEqual('HTMLDivElement', body_first_child.__proto__.constructor.name);
  testing.expectEqual(null, $('#para-empty').firstChild.firstChild);
</script>

<script id=lastChild>
  let last_child = content.