ht = '250px';
  content.style.width = '250px';

  scroller.appendChild(content);

  const scrollTimeline = new ScrollTimeline(
      { source: scroller, orientation: 'block' });

  assert_equals(scrollTimeline.currentTime, null);
}, 'currentTime should be null for an unattached source');
</script>

<div id='notAScroller' class='scroller' style='overflow: visible;'>
  <div class='content'></div>
</div>
<script>
test(function() {
  const scroller = document.querySelector('#notAScroller');
  const scrollTimeli