<!DOCTYPE html>
<!-- Passes if the word "test" is visible -->
<div style="border-radius:2px;overflow:hidden;">
  <div style="overflow:hidden;">
    <div style="transform: translateZ(0);"></div>
  </div>

  <!-- This div has zero height because its child is floating. Nevertheless the
  child should get the rounded clip mask applied to it. It is indirectly
  composited due to overlapping the above div -->
  <div style="position:relative;">
    <div style="float:left">test</div>
  </div>
</div>