gecko-dev/gfx/tests/crashtests/1704321-1.html

<style>
:root {
  perspective: 1px;
}
#a {
  -webkit-mask-image: url(data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=);
}
:not(defs) {
  transform: rotatex(1deg);
}
</style>
<a style="-webkit-mask-image: url(#x)">
<ul id="a">x</ul>