chromium/third_party/blink/web_tests/animations/web-animations/infinite-duration.html

<!DOCTYPE html>
<meta charset=utf-8>
<title>Animating with infinite duration</title>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<body>
<script>
"use strict";

test(function(t) {
  // (crbug.com/1088218) This is a regression test to prevent a crash.
  // This test passes as long as there is no crash.
  const duration = 18446744073709551534;
  function createAnimation(keyframes, effect, className) {
    const div = document.createElement("div");
    document.body.appendChild(div);
    effect.duration = duration;
    div.animate(keyframes, effect);
  }
  createAnimation({ opacity: [0, 1] },
                  { fill: "backwards", iterationStart: 18446744073709551383 },
                    "fill-backwards-with-delay-iterationstart");
}, "An animation with infinite duraction won't crash.");
</script>
</body>