chromium/third_party/blink/web_tests/paint/overflow/fixed-children-should-not-scroll.html

<!DOCTYPE html>
<script src="../../resources/run-after-layout-and-paint.js"></script>
<style>
#bloat {
    height: 10000px;
}

#fixed {
    position: fixed;
    left: 300px;
    top: 200px;
    width: 100px;
    height: 100px;
    background-color: green;
}

#fixed-child {
    margin-left: 25px;
    margin-top: 25px;
    width: 50px;
    height: 50px;
    background-color: blue;
}

::-webkit-scrollbar {
    width: 0px;
    height: 0px;
}
</style>
<div id="bloat"></div>
<div id="fixed">
    <div id="fixed-child"></div>
</div>
<script>
runAfterLayoutAndPaint(function() {
   window.scrollTo(0, 100);
}, true);
</script>