chromium/third_party/blink/web_tests/animations/events/empty-keyframe-triggers.event.html

<!doctype html>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<style>
  @keyframes anim { }
  #target { animation: anim; }
</style>
<div id="target"></div>
<script>
  var test1 = async_test('Check whether the animationstart is fired for an empty @keyframe block');
  target.addEventListener('animationstart', function(event) {
      test1.done();
  });
</script>