@jpolitz I am going to merge in this patch. It fixes a bug in Stopify that @LeifAndersen identified (#481). I do not believe it breaks anything else. But, do look at the two unit tests that I've added -- one that still fails

The problem would arise when stopifying a var within a block or loop at the top-level. For various reasons, ElementaryJS does wraps the entire student code in a thunk, so student code would never update top-level variables, which is why this problem would never arise Ocelot.