<!DOCTYPE html>
<script>
    onload = function() {
        var elm = document.getElementById('elm');
        document.body.offsetTop; // trigger layout
        elm.style.display = 'block';
    }
</script>
<p>Test inserting a block in the middle of inline content that has an anonymous wrapper block around it.</p>
<p>There should be three lines below with the word "PASS". Letter spacing is expected to vary</p>
<div style="-webkit-columns:4; -webkit-column-gap:0; width:4em; orphans:1; widows:1;">
    <div style="-webkit-column-span:all;">PASS</div>
    P<br>P
    <div id="elm" style="display:none;">A</div>
    A<br>S<br>S<br>S<br>S
</div>