88846 Migrate mac.dart to null safety (tool, cla: yes, waiting for tree to go green, a: null-safety)

88850 Migrate some flutter_tools tests to null safety (tool, cla: yes, waiting for tree to go green, a: null-safety)

88851 Migrate ios_deploy to null safety (tool, cla: yes, waiting for tree to go green, a: null-safety)

88857 Fixed leak and removed no-shuffle tag in widgets/debug_test.dart (a: tests, team, framework, cla: yes, waiting for tree to go green, tech-debt)

88877 Fixed leak and removed no-shuffle tag in platform_view_test.dart (a: tests, team, framework, cla: yes, waiting for tree to go green, tech-debt)