It appears that this can be fixed by intercepting occasions
when Jint returns an ExpandoObject but the desired return type
is simply object. In this scenario we must return
a Dictionary<string,object> instead of a simple object, or else
Jint freaks out should we try to stringify it later.
I also added a second test to prove that making this change hasn't
broken the way we expect Jint to work for us.
