<!DOCTYPE html>
<style>
    span { display:inline-block; width:1em; }
</style>
<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>
PASS<br>
<span>P</span><span>A</span><span>S</span><span>S</span><br>
<span>P</span><span>A</span><span>S</span><span>S</span><br>