65528 Reland “Nnbd widgets” (a: accessibility, cla: yes, f: cupertino, framework, waiting for tree to go green)

65568 Remove unused ‘dart:async’ imports. (a: accessibility, a: internationalization, a: tests, cla: yes, f: cupertino, f: material design, framework, team, tool)

65579 Move the registration of the restoration channel to binding initialization (cla: yes, framework, waiting for tree to go green)

65584 List tile docs (cla: yes, f: material design, framework, waiting for tree to go green)

65602 Reland “perf test for measuring scroll smoothness” (a: tests, cla: yes, framework, team, waiting for tree to go green)