18638 Add tests for FlBinaryMessenger, FlBasicMessageChannel, FlMethodChannel (cla: yes)

18641 Fix FlValue functions not marked for export (cla: yes)

18645 Platform resolved locale and Android localization refactor (cla: yes, platform-android, platform-ios, waiting for tree to go green)

18646 Roll Fuchsia Mac SDK from Id94G… to xRJHj… (cla: yes, waiting for tree to go green)

18647 Roll Fuchsia Linux SDK from V1XR3… to 8sYPn… (cla: yes, waiting for tree to go green)

18648 Minimize child DOM node moves in many-to-many update (cla: yes)

18649 check the branch flags (cla: yes)