Quick follow-on to #17788. If there is no bound `self` parameter, we can reuse the existing `CallArgument{,Type}s`, and we can use a straight `Vec` instead of a `VecDeque`.
Quick follow-on to #17788. If there is no bound `self` parameter, we can reuse the existing `CallArgument{,Type}s`, and we can use a straight `Vec` instead of a `VecDeque`.