LayoutTests/webanimations/scheduling-of-animation-without-renderer.html

<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<div></div>
<script>

promise_test(async () => {
    const target = document.querySelector("div");
    const animation = document.querySelector("div").animate({ marginLeft: "100px" }, 1000);
    await animation.ready;

    animation.currentTime = 100;
    assert_equals(internals.timeToNextAnimationTick(animation), 0, "Animation needs immediate resolution when running with a renderer.");

    target.style.display = "none";
    assert_equals(getComputedStyle(target).display, "none");
    assert_equals(internals.timeToNextAnimationTick(animation), 900, "Animation will not need to be resolved until complete when running without a renderer.");
}, "Computing the time until the next tick for an effect targeting an element losing its renderer.");

</script>