68642 Sound null safety for framework and flutter_test (a: tests, cla: yes, d: examples, f: cupertino, f: material design, framework, team)

68729 App.framework must support iOS 8 for older Flutter projects (cla: yes, d: examples, platform-ios, team, tool, waiting for tree to go green)

68736 Remove nullOk in MediaQuery.of (cla: yes, d: examples, f: cupertino, f: material design, framework, team)

68744 Migrate all of examples/layers to sound null safety (cla: yes, d: examples, team)

68905 Remove nullOk parameter from Cupertino color resolution APIs (cla: yes, d: examples, f: cupertino, f: material design, framework, team)