chromium/third_party/blink/web_tests/compositing/overflow/reparented-overlay-scrollbars-should-respect-ancestor-clip.html

<!DOCTYPE HTML>
<!--
    This test ensures that reparented overlay scrollbars still respect
    clips applied by a tree-order ancestor, even if that ancestor is
    not an ancestor in the compositing layer tree.
-->
<meta name=fuzzy content="maxDifference=0-1;totalPixels=0-300">
<script>
if (window.internals) {
    internals.useMockOverlayScrollbars();
    internals.settings.setPreferCompositingToLCDTextEnabled(true);
}
</script>
<style>
#clipper {
    overflow: hidden;
    width: 400px;
    height: 100px;
    margin: 10px;
}

#scroller {
    overflow: scroll;
    width: 300px;
    height: 300px;
    position: relative;
    top: 10px;
}

#fixed {
    position: fixed;
    background: blue;
    left: 90px;
    width: 10px;
    height: 10px;
}

#scrolled {
    position: relative;
    background: green;
    width: 80px;
    height: 500px;
}
</style>
<div id='clipper'>
    <div id='scroller'>
        <div id='fixed'></div>
        <div id='scrolled'></div>
    </div>
</div>