gecko-dev/gfx/webrender/tests/bug_143.html

<style>
  div {
    background-size: cover;
    border-radius: 10px;
    width: 100px;
    height: 100px;
    //border:0.5px solid red;
    background-image: url(http://www.google.com/favicon.ico);
  }
</style>
<div></div>