62452 Fix “unresolved doc reference” in widgets layer - part 1 (cla: yes, framework, waiting for tree to go green)

62462 separate scroll until visible implementation for lower level accessibility  (a: tests, cla: yes, framework, waiting for tree to go green)

62471 Fix Border.symmetric: phase 3 (cla: yes, framework)

62473 Fix ‘unresolved doc reference’ for material A-D (cla: yes, f: cupertino, f: material design, framework, waiting for tree to go green)

62485 migrate animation to nullsafety (cla: yes, framework, waiting for tree to go green)

62495 Implement size analyzer to unzip & parse APK and AOT size snapshot to generate analysis json (cla: yes, team, tool)