41625 Update DefaultTabController to allow for zero tabs (cla: yes, f: material design, framework, waiting for tree to go green)

41629 [Material] Fix Tooltip to respect ambient Directionality (cla: yes, f: material design, framework, waiting for tree to go green)

41632 fix confusing ‘popupTheme’ variable name in a MaterialBannerTheme method (cla: yes, f: material design, framework)

41640 some formatting changes (cla: yes, f: material design, framework, team, tool, waiting for tree to go green)

41644 indent formal parameters correctly (cla: yes, f: cupertino, f: material design, framework, team, tool, waiting for tree to go green)

41646 replace package:vm_service_client with package:vm_service in the devicelab project (cla: yes, team, tool, waiting for tree to go green)