Unfortunately Jint still chokes in this case if the expando contains
further nested expandos. It turns out that I need to do this
recursively for it to always work.
We also have trouble with IEnumerable types. They also can't be
round-tripped from/to JSON when they aren't deserialized as a very
specific type.
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.
