[XeTeX] Eastern Arabic numerals in math environment

[Nathan Sidoli]

Is is possible to use Eastern Arabic numerals inside a math environment, 
say inside \frac{}{} (such as \frac{٥}{٢})? When I try this with unicode 
input, I get no errors, but blank output. When I enter a RL environment 
within \frac, using bidi, I get errors. (This must have something to do 
with \frac because I can generally use bidi within a math environment to 
get Easter Arabic numerals.)

When I try to change the math environment's digits font for the whole 
text (say using \usepackage{mathspec} -> \setmathsfont(Digits){Some 
Arabic Font}), it uses the right font, but it uses the Western Arabic 
numeral set, not the Eastern Arabic set.