73780 Fix single ToggleButton border painting bugs (cla: yes, f: material design, framework, waiting for tree to go green, will affect goldens)

73829 Expose DialogRoutes for state restoration support (cla: yes, f: cupertino, f: material design, framework, waiting for tree to go green)

73846 fix a tap gesture exception (cla: yes, framework, waiting for tree to go green)

73882 Mac context menu (cla: yes, f: cupertino, f: material design, framework)

73894 Added ButtonStyle.alignment property (cla: yes, f: material design, framework)

73895 Flutter 1.26 candidate.10 (cla: yes, f: material design, framework, waiting for tree to go green)