LayoutTests/fast/text/fixed-pitch-control-characters.html

<style>
    div { font-family: 'Ahem'; font-size: 25px; width: 100px; color: green; background-color: red; }
</style>
<div>
    <span>x&#x0c;x</span><span>xx</span>
<!--
    <span>x&#x0c;e&#x301;</span><span>xx</span>
-->
    <span>x&#x0b;x</span><span>xx</span>
<!--
    <span>x&#x0b;e&#x301;</span><span>xx</span>
-->
</div>