third_party/WebKit/LayoutTests/animations/neutral-keyframe-crashtest.html

<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<div id="f"></div>
<script>
async_test(function(test) {
  f.animate([{"marginTop": "auto"}],
      {iterationStart: 0.5, fill: 'forwards'});
  requestAnimationFrame(() => {
    f.animate([{"marginTop": "auto"}],
        {iterationStart: 0.5, fill: 'forwards'});
    test.done();
  });
}, "Using a neutral key frame doesn't crash.");
</script>