LayoutTests/webanimations/animation-opacity-animation-crash.html

<div id="target" style="width: 100px; height: 100px; background-color: black;"></div>
<script>

const animation = new Animation(new KeyframeEffect(document.getElementById("target"), [
    { opacity: 1 },
    { opacity: 0 }
]));
animation.startTime = 0;
animation.effect.timing.duration = 1000;

</script>