29633 Download secondary SDK (cla: yes, tool)

29638 Fix transition to stock details (cla: yes, team, team: gallery)

29641 Fix links on homepage of API docs (cla: yes, d: api docs, framework)

29644 Cupertino localization step 3: in-place move some material tools around to make room for cupertino (cla: yes, f: cupertino, f: material design, framework)

29650 Cupertino localization step 4: let generated date localization combine material and cupertino locales (cla: yes, f: cupertino, f: material design, framework)

29654 Include brackets on OutlineButton doc (cla: yes, d: api docs, f: material design, framework)

29669 Speed up CI via mojave-flutter image (a: tests, cla: yes, team)