message: ExactSizeIterator for SmallMap::iter
diff: @@ -148,6 +148,8 @@ impl<'a, K: 'a, V: 'a> Iterator for VMIter<'a, K, V> {
  def_iter!();
  }
  +impl<'a, K: 'a, V: 'a> ExactSizeIterator for VMIter<'a, K, V> {}
  +
  impl<'a, K: 'a, V: 'a> VMIter<'a, K, V> {
  fn map(b: &Bucket<K, V>) -> (&K, &V) {
  (&b.key, &b.value)
  