30811 Make coverage, like, really fast (cla: yes, tool)

30814 Fix StatefulWidget and StatelessWidget Sample Documentation (cla: yes, d: api docs, framework)

30815 Make CupertinoNavigationBarBackButton correctly return an assert error (cla: yes, f: cupertino)

30818 New flag to flutter drive to skip installing fresh app on device (cla: yes, tool)

30828 add golden tests for CupertinoDatePicker (cla: yes, f: cupertino, f: date/time picker, framework)

30829 Keep hover annotation layers in sync with the mouse detector. (a: desktop, cla: yes, framework)

30832 Bump Android build tools to 28.0.3 in Dockerfile (cla: yes, team)