chromium/third_party/blink/web_tests/paint/invalidation/flexbox/repaint-opacity-change-expected.html

<!DOCTYPE html>
<style>
.item {
  margin: 10px;
  margin-top: 20px;
  padding: 10px;
  background: green;
</style>
<div class="item" style="margin-top: 18px"></div>
<div class="item" style="opacity: 0.5; margin-top: 20px"></div>
</body>