Fixes https://github.com/flutter/flutter/issues/126690.

Encountered while testing https://github.com/flutter/flutter/pull/132406. Updates the signature to be in line with the [current typedef](https://github.com/flutter/flutter/blob/b3096225e0ebc005ed678fa7a9f03164caba1d73/packages/integration_test/lib/common.dart#L26).