74899 Remove “unnecessary” imports in material/ (cla: yes, f: material design, framework, waiting for tree to go green)

74906 Improve Dropdown Menu (cla: yes, f: material design, framework, waiting for tree to go green)

74937 [flutter_releases] Flutter 1.26.0-17.1.pre Dev - Revert vm_service, other packages from pub roll (a: tests, cla: yes, f: cupertino, f: material design, framework, team, tool)

74949 Added ButtonStyle.splashFactory and NoSplash.splashFactory (cla: yes, f: material design, framework, waiting for tree to go green)

75005 Remove “unnecessary” imports in material (cla: yes, f: cupertino, f: material design, framework, waiting for tree to go green)