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chromium/third_party/blink/web_tests/compositing/resources/iframe-graphics-tree-changes-parents-does-not-frame.html 

<!doctype HTML>

<style>
#parent {
  width: 100px;
  height: 100px;
  background-color: lightblue;
}
#child {
  width: 50px;
  height: 50px;
  background-color: blue;
  will-change: transform;
}
</style>

<div id="parent">
  <div id="child"></div>
</div>

<script src="../../resources/run-after-layout-and-paint.js"></script>
<script>
runAfterLayoutAndPaint(function() {
  document.getElementById("parent").style = "height: 500px;";
  parent.postMessage('done', '*');
});
</script>