chromium/third_party/blink/web_tests/fast/multicol/dynamic/insert-block-into-spanner.html

<!DOCTYPE html>
<script>
    onload = function() {
        var elm = document.getElementById('elm');
        document.body.offsetTop; // trigger layout
        elm.style.display = 'block';
    }
</script>
<p>Test insertion of a block inside a spanner.</p>
<p>You should see the word "PASS" below.</p>
<div style="-webkit-columns:5; -webkit-column-gap:0;">
    <div style="-webkit-column-span:all;"><div id="elm" style="display:none;">PASS</div></div>
</div>