<style>
  * {
      -webkit-animation: mykeyframes infinite;
  }
  *:root{
      animation-duration: 1s;
      animation-direction: alternate, normal;
  }
  @keyframes mykeyframes { }
</style>
<!-- Original crash is only reproducible with an external script. -->
<script src="undo-with-disconnected-editable-element-crash.js"></script>
<body>
  <input id="inputElement" value="A" hidden=""/>
</body>