68160 Convert some more widget tests to NNBD (a: accessibility, cla: yes, framework, waiting for tree to go green)

68173 [NNBD] Migrate more widget tests to NNBD (a: accessibility, cla: yes, framework, waiting for tree to go green)

68301 use_is_even_rather_than_modulo (a: accessibility, a: tests, cla: yes, f: material design, framework, team)

68409 [flutter_tools] add –android-gradle-daemon option, use in devicelab (a: accessibility, cla: yes, team, tool)

68489 Revert “[flutter_tools] add –android-gradle-daemon option, use in devicelab” (a: accessibility, cla: yes, team, tool)