<!DOCTYPE html>
<html>
    <head>
        <title>Remove spanner before column row</title>
        <script>
            function test() {
                var elm = document.getElementById('elm');
                elm.offsetTop; // trigger layout
                elm.style.display = 'none';
            }
        </script>
    </head>
    <body onload="test()">
        <p>There should be a black square below, and nothing else.</p>
        <div style="width:32em;">
            <div style="width:10em; height:5em; color:black; background:black;"></div>
            <div style="-webkit-columns:3; columns:3; -webkit-column-gap:1em; column-gap:1em; line-height:5em; orphans:1; widows:1;">
                <div id="elm" style="-webkit-column-span:all; column-span:all;">x</div>
                <div style="color:black; background:black;">x</div>
            </div>
        </div>
    </body>
</html>