lower case blackboard bold issues, Chrome and possibly IE8

From the user group, the lower case a and c don't show (missing characters boxes are shown instead).

The report was made for IE8 and Chrome(?) on WinXP SP3. I can reproduce it for Chrome 27 on Win7, but not IE8 on Win7 (using the Microsoft testing VM).

IIRC, the MathJax fonts don't include the relevant characters, so I'm guessing this is a browser-specific fallback issue?