chromium/third_party/blink/web_tests/paint/invalidation/compositing/become-composited-zero-offset.html

<!DOCTYPE html>
<iframe style="border: none; position: absolute; z-index: 1; width: 100px; left: 200px"
    srcdoc="SHOULD NOT DISAPPEAR"></iframe>
<div id="trigger" style="width: 100%; height: 100px"></div>
<script src="../../../resources/run-after-layout-and-paint.js"></script>
<script>
onload = function() {
  runAfterLayoutAndPaint(function() {
    trigger.style.willChange = 'transform';
  }, true);
};
</script>