message: Fix incorrect type in iterator.
diff: @@ -378,7 +378,7 @@ public:
  // Support result type iteration.
  using result_type_iterator =
  - ResultTypeIterator<const Instruction, const Value>;
  + ResultTypeIterator<const Instruction, const Type>;
  result_type_iterator result_type_begin() const;
  result_type_iterator result_type_end() const;
  