Work around redundant hint with unnecessary null comparison.
Work around redundant hint with unnecessary null comparison.

This should fix analyzer bot failures triggered by
https://dart-review.googlesource.com/c/sdk/+/155926.

Bug: https://github.com/dart-lang/sdk/issues/43051
Change-Id: Ie4650a72611c63798054b4f4aad9dfa7d76ad0af
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/158486
Auto-Submit: Paul Berry <72d414e3a99fb120308437779d51667bcc0984eb@google.com>
Reviewed-by: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>
Reviewed-by: Konstantin Shcheglov <09e4d7516628963212bf4aace2f97603d2b706e4@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk