LayoutTests/fast/dom/firstline-fixed-crash.html

<script>
if (window.testRunner)
    testRunner.dumpAsText();
</script>
<style>
*:nth-child(2):first-line { margin-bottom: 1px; }</style>
<div contentEditable>
<a style="position: fixed;">
This text should render without crashing
</div>...