Incorrect translation of poly type in Stream

[PhucVH888]

This issue is similar to the issue #809 . The main difference is that the issue occurs in Stream.

active class Foo[t]
  stream produce(var n : int, v : t) : t
    while n>0 do
      yield(v)
      n -= 1
    end
  end
end
active class Main
  def main() : unit
    val foo = new Foo[int]
    val s = foo!produce(10, 42)
  end
end

The error message is similar to #809

failedPolyTypeStreamWithObject_src/Foo.encore.c:228:46: error: use of undeclared identifier '_enc__type_t'
  encore_trace_polymorphic_variable((*_ctx), _enc__type_t, _enc__arg_v);
                                             ^
1 error generated.
 *** Compilation failed with exit code 1 ***

[supercooldave]

It looks like it could be the same error. Perhaps merging this issue with the previous.