Add vec_deque::Iter::as_slices and friends Add the following methods, that work similarly to VecDeque::as_slices: - alloc::collections::vec_deque::Iter::as_slices - alloc::collections::vec_deque::IterMut::into_slices - alloc::collections::vec_deque::IterMut::as_slices - alloc::collections::vec_deque::IterMut::as_mut_slices Obtaining slices from a VecDeque iterator was not previously possible.