workers/worker-request-animation-frame.html

<!DOCTYPE html>
<html>
<head>
<title>raf time in dedicated workers</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<body>
<script>
  async function waitForMessage(worker) {
    return new Promise(resolve => {
      worker.onmessage = event => resolve(event);
    });
  }

  promise_test(t => {
    const worker = new Worker('support/worker-request-animation-frame.js');
    const message = waitForMessage(worker);
    worker.postMessage('');
    message.then((event) => {
      const raf_time = event.data;
      assert_true(performance.now() >= raf_time,
                  'raf time cannot exceed time of page load');
    });
    return message;
  }, 'requestAnimationTime reports frame time relative to worker load');
</script>