84145 Migrate integration_tests/channels to null safety (team, framework, cla: yes, waiting for tree to go green, a: null-safety, tech-debt)

84153 Migrate dartdoc to null safety (team, cla: yes, waiting for tree to go green, a: null-safety, tech-debt)

84156 Re-land “Migrate android_semantics_testing to null safety (#84136)” (team, a: accessibility, cla: yes, waiting for tree to go green, a: null-safety, tech-debt)

84594 Clean up NestedScrollView TODOs (team, framework, cla: yes, waiting for tree to go green, tech-debt)