Radius inside radius doesn't work anymore

[paulrouget]

This used to work.

Maybe it's a regression due to servo/servo#9810

<style>
  .green {
    overflow: hidden;
    border-radius: 50px;
    background: green;
    padding: 50px;
  }

  .red {
    background: red;
    border-radius: 50%;
    width: 100px;
    height: 100px
  }
</style>

<div class="green">
  <div class="red"></div>
</div>