c15d215653
Null-aware calls, like `v?.extMethod()` don't require `v` to be non-nullable, even if `extMethod` was declared on a non-nullable type. Tested: added a new test. Change-Id: I113ecde21e480bcd467367d0954b721c2ad9f7e0 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/301982 Reviewed-by: Paul Berry <paulberry@google.com>