28159 [Material] Expand BottomNavigationBar API (reprise) (cla: no, f: material design, framework)

28163 [Material] Add ability to set shadow color and selected shadow color for chips and for chip themes (cla: yes, f: material design, framework)

28166 Add some more CupertinoPicker doc (cla: yes, d: api docs, f: cupertino, framework)

28168 [flutter_tool,fuchsia_tester] Only require a test source dir for coverage (a: tests, cla: yes, tool, ○ platform-fuchsia)

28169 Add/rewrite tests for FocusScope. (a: text input, cla: yes, framework)

28171 deploy to .dev firebase projects. (cla: yes, team)

28172 Add backgroundColor argument to TextStyle for convenience (cla: yes, framework)