\frac without curly braces inconsistent with Mathjax

[cdelker]

Mathjax renders these two \fracs the same, as 1/2 x:

\frac 1 2 x + \frac 12x

but latex2mathml converts the second one into 12/x.

Reference cdelker/ziamath#6.

[roniemartinez]

@all-contributors please add @cdelker for bug

[allcontributors[bot]]

@roniemartinez

I've put up a pull request to add @cdelker! :tada: