<style>
  @keyframes a0 {
    from {
      -webkit-mask-box-image-source: url()
    }
  }
  :not(:target)::marker {
    animation-name: a0;
    animation-duration: 1ms;
  }
</style>
<li>PASS</li>
<script>
    if (window.testRunner) {
        testRunner.dumpAsText();
    }
</script>