38441 Fix getOffsetToReveal for growthDirection reversed and AxisDirection down or right (cla: yes, framework)

38462 Revert “Roll engine ff49ca1c6e5b..7dfdfc6faeb6 (52 commits)” (cla: yes, engine)

38463 Do not construct arguments to _focusDebug when running in non-debug modes (cla: yes, framework)

38467 [Material] Add splashColor to FAB and FAB ThemeData (cla: yes, f: material design, framework)

38472 [flutter_tool] Fix bug in manifest yaml validation (cla: yes, tool)

38486 Catch errors thrown into the Zone by json_rpc (cla: yes, tool)

38491 Update CONTRIBUTING.md (cla: yes, team)