80995 Add trailing commas in packages/flutter/test/{painting,physics,semantics,schedule} (framework, a: accessibility, cla: yes, waiting for tree to go green)

81065 Add trailing commas in packages/flutter/test/rendering (framework, a: accessibility, cla: yes)

81083 Make compareTo more robust in semantics.dart (framework, a: accessibility, cla: yes, waiting for tree to go green)

81226 Revert “Migrate to ChannelBuffers.push” (a: tests, team, framework, f: material design, a: accessibility, cla: yes, f: cupertino, d: examples)

81235 Migrate to ChannelBuffers.push (a: tests, team, framework, f: material design, a: accessibility, cla: yes, f: cupertino, d: examples, waiting for tree to go green)