26586 Added Sample code for Stack widget (cla: yes, d: api docs, framework)

26589 Do not exit tool if parts of fuchsia workflow fail (cla: yes, tool, ○ platform-fuchsia)

26592 Prevent crash when calling lerp for IconThemeData with null arguments (cla: yes, framework)

26593 Support running macOS prebuilt application (cla: yes, tool, ⌘‬ platform-mac)

26596 Roll engine to 5983e34a3c0e1217da7e8bbe9f2fe685048fe259 (cla: yes)

26597 [Material] Implement App Bar Theme (cla: yes, f: material design, framework)