chromium/third_party/blink/web_tests/external/wpt/css/css-flexbox/flex-item-contains-size-layout-001.html

<!doctype html>
<html class=reftest-wait>
<link rel="author" title="David Grogan" href="mailto:[email protected]">
<link rel="help" href="">
<meta name="assert" content="Flex items with contain: layout size are sized properly.">
<link rel="bookmark" href="https://crbug.com/1108675">
<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
<style>
#flex {
  display: flex;
  width: 100px;
  height: 100px;
}
#grid {
  background-color: green;
  display: grid;
  flex: 1;
  contain: layout size;
}
.item {
  height: 50px;
  width: 50px;
}
#reference-overlapped-red {
  position: absolute;
  background-color: red;
  width: 100px;
  height: 100px;
  z-index: -1;
}
</style>

<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
<div id="reference-overlapped-red"></div>

<div id="flex">
  <div id="grid" data-expected-height=100 data-expected-width=100>
    <div class="item"></div>
  </div>
</div>

<script>
  document.body.offsetTop;
  let item = document.querySelector(".item");
  let cloned = item.cloneNode(true);
  let parent = item.parentElement;
  parent.appendChild(cloned);
  document.documentElement.classList.remove("reftest-wait");
</script>