<!DOCTYPE html>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>

<iframe id=frame></iframe>

<script>
var handle = async_test('Animation time should tick consistently across frames');
var baseTime = document.timeline.currentTime;
var frameBaseTime = frame.contentDocument.timeline.currentTime;
setTimeout(function() {
  var start = performance.now();
  while (performance.now() - start < 30);
  var delta = document.timeline.currentTime - baseTime;

  var start = performance.now();
  while (performance.now() - start < 30);
  var frameDelta = frame.contentDocument.timeline.currentTime - frameBaseTime;

  handle.step(() => assert_equals(Math.round(delta), Math.round(frameDelta)));
  handle.done();
});
</script>