* If there are no return statements, suggest a `void` or `Future<void>`
return type.
* Visit yield statements as well, to suggest proper return types in
generators.
* Combine the 'return type computers' in extract_method.dart and
add_return_type.dart int one.
Change-Id: I223a50b11e7e77183f166c193fa74b8a2800127e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/401862
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Sam Rawlins
e4b9170ca4