Gizmo: accumulate results in map()

[jasondouglas]

Other finals seem to work fine. For example this works:

g.Emit({
    "films" : g.V().Has("/film/film/directed_by", director_id).TagArray()
});

But this gets: {"error" : "(anonymous): Line 6:1 Unexpected token } (and 3 more errors)"}

g.Emit({
    "films" : g.V().Has("/film/film/directed_by", director_id).ForEach(function(d){
      return d;
    });
});

... or any other variation of function body (like a nested g.Emit());

You might wonder what I'm trying to do... it's format an entire tree. g.Emit() seems to be the only way to do optional fields in an object, so I was trying to figure out how to nest that.

[barakmich]

This is a bug in the Emit function I think, combined with not accumulating the return values on ForEach (where not undefined), which is straightforward enough.

[dennwc]

There is no error on HEAD for first example.
Will implement accumulation a bit later.

[iddan]

Correction: .forEach() shouldn't accumulate results, .map() should.

[iddan]

Closing this as #878 will not include steps that accept a function.