76387 Refactor tabbar code sample (cla: yes, d: api docs, documentation, f: material design, framework, waiting for tree to go green)

76493 Add menuMaxHeight for DropdownButton (cla: yes, f: material design, framework, waiting for tree to go green)

76532 [Fonts] Improve update_icons script (cla: yes, f: material design, framework, team)

76542 Add a EdgeInsetsDirectional.all constructor similar to EdgeInsets.all (cla: yes, framework, waiting for tree to go green)

76600 Dispose image when cache clear (cla: yes, framework, waiting for tree to go green)

76607 [Fonts] Update material icons (cla: yes, f: material design, framework)