LayoutTests/compositing/overflow/overflow-change-recomputes-overlap.html

<!DOCTYPE html>
 <html class="reftest-wait">
 <head>
     <style>
         .composited {
           width: 200px;
           height: 200px;
           background: green;
           position: relative;
           transform: translateZ(0px);
           display: flow-root;
         }

         .overflow {
           width: 100px;
           height: 100px;
           background: red;
         }

        .overlap-overflow {
           width: 200px;
           height: 200px;
           background: green;
           position: relative;
         }

     </style>
 </head>

 <script>
     function waitAndResizeContainers() {
         requestAnimationFrame(() => requestAnimationFrame(() => {
             overflow.style.marginTop = "200px";
             document.documentElement.classList.remove("reftest-wait");
         }));
     }
 </script>
 <body onload="waitAndResizeContainers()">

     <div class="composited">
         <div id="overflow" class="overflow"></div>
     </div>
     <div class="overlap-overflow"></div>
 </body>