chromium/third_party/blink/web_tests/paint/invalidation/compositing/invalidate-paint-in-iframe-in-composited-layer.html

<!DOCTYPE html>
<html>
<head>
<script src="../resources/text-based-repaint.js"></script>
<script>
window.onload = function() {
    runRepaintAndPixelTest();
};

function repaintTest() {
    document.getElementsByTagName('iframe')[0]
        .contentDocument
        .getElementsByTagName('div')[0]
        .style
        .backgroundColor = 'green';
}
</script>
</head>
<div style="height: 400px"></div>
<div style="height: 200px; width: 200px; will-change: transform;">
    <iframe srcdoc="<div style='height: 50px; width: 50px; background-color: red;'></div>"></iframe>
</div>