vertical-scrollbar-shrink-container-width.html

<!DOCTYPE html>
<p>Test decreasing the width of the containing block of a scrollable container with percent width.</p>
<p>One vertical scrollbar should be seen below.</p>
<div id="target" style="width:700px;">
    <div style="width:50%; height:400px; overflow-y:scroll;"></div>
</div>
<script src="../../../resources/run-after-layout-and-paint.js"></script>
<script>
    function changeSize() {
        document.getElementById('target').style.width = '300px';
    }
    runAfterLayoutAndPaint(changeSize, true);
</script>

chromium/third_party/blink/web_tests/paint/invalidation/scroll/vertical-scrollbar-shrink-container-width.html