LayoutTests/platform/mac/fast/text/x-height.html

<p>
    Test x-height caluclation.
</p>
<p>
    This box is 5ex by 5ex at 100px Arial.
</p>
<div id="target" style="font: 100px arial; height: 5ex; width: 5ex; background-color: blue;"></div>