773b42f4fb
## Description This PR removes `DropdownMenu` usage of Leader/Follower. Leader/Follower positioning was introduced in https://github.com/flutter/flutter/pull/154667 which uses Leader/Follower approach to fix some weird positioning issues (such as https://github.com/flutter/flutter/issues/149037). Unfortunately, it also introduces some regressions, see: - https://github.com/flutter/flutter/issues/157916 - https://github.com/flutter/flutter/issues/158924 Because https://github.com/flutter/flutter/pull/154667 is already included in the beta channel, cherry-picking this PR should be considered. ## Context This PR is not a full revert and keeps Leader/Follower usage in `MenuAnchor` because this usage is optional and doesn't cause any regression. There are some ongoing work which might fix or mitigate this problem: - https://github.com/flutter/flutter/pull/157921 - https://github.com/flutter/flutter/pull/158255 ## Related Issue Fixes https://github.com/flutter/flutter/issues/157916 Fixes https://github.com/flutter/flutter/issues/158924 Reopens https://github.com/flutter/flutter/issues/123395 Reopens https://github.com/flutter/flutter/issues/149037 Reopens https://github.com/flutter/flutter/issues/151856