<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/web-animations-1/#the-effecttiming-dictionaries">
<style>
.scroller {
  overflow: auto;
  height: 100px;
  width: 100px;
  will-change: transform;
}

.contents {
  height: 1000px;
  width: 100%;
}
</style>
<div class="scroller">
  <div class="contents"></div>
</div>
<script>
  // Test passes if it does not crash.
  // Scroll timeline animations are progress-based and not compatible with
  // delays specified in milliseconds.
  const timeline = new ScrollTimeline();
  const options = {
    timeline: timeline,
    endDelay: 200
  };
  const keyframes = { opacity: [0, 1]};
  const element = document.querySelector('.contents');
  element.animate(keyframes, options);
</script>
