LayoutTests/fast/css/letter-spacing-calc-with-font-relative-lengths-crash.html

<!doctype>
<style>
  body {
      text-rendering: optimizeLegibility;
      letter-spacing: calc(1ex + 1ch);
  }
</style>
<script>
    if (window.internals) {
        testRunner.dumpAsText();
    }
</script>
<p>This test passes if it does not crash.</p>