gecko-dev/layout/base/crashtests/1516286-empty-mask.html

<style>
* {
  -webkit-transform: scaleY(96);
  float: left;
  border-top: 4em solid
}
#a {
  clip-path: polygon(0px 0px, 1px 0px, 48px 1px);
}
</style>
<time>
<ul>
<li id="a">
A