horizontal-scrollbar-grow-container-height.html

<!DOCTYPE html>
<p>Test increasing the height of the containing block of a scrollable container with percent height.</p>
<p>One horizontal scrollbar should be seen below.</p>
<div id="target" style="height:250px;">
    <div style="height:50%; overflow-x:scroll;"></div>
</div>
<script src="../../../resources/run-after-layout-and-paint.js"></script>
<script>
    function changeSize() {
        document.getElementById('target').style.height = '450px';
    }
    runAfterLayoutAndPaint(changeSize, true);
</script>

chromium/third_party/blink/web_tests/paint/invalidation/scroll/horizontal-scrollbar-grow-container-height.html