30530 Let docker image install fastlane too for Linux (cla: yes)

30531 Correct MaterialButton disabledColor (cla: yes)

30535 Correctly synthesise event buttons (cla: yes, waiting for tree to go green)

30537 Embedded images and added variations to ListTile sample code (cla: yes, d: api docs, f: material design, framework)

30562 Replace flutter.io with flutter.dev (a: first hour, a: quality, cla: yes)

30563 Fixed a typo in the Expanded API doc (cla: yes, d: api docs, framework)

30570 Bump dartdocs to 0.28.3+1 (cla: yes)

30572 [Material] Adaptive Slider constructor (cla: yes, f: material design, framework)