34081 Report async callback errors that currently go unreported. (cla: yes, tool)

34084 make running on web spooky (cla: yes, tool)

34085 Revert “Roll engine to 086b5a48d6acdb64dd7b2a4cbf9dd620c54812b9” (cla: yes)

34086 Add recognizer compatibility API (cla: yes)

34088 Revert “Roll engine 0602dbb27547..06dbe28e33e5 (13 commits)” (cla: yes)

34090 More verification on flutter build web, add tests and cleanup (cla: yes, tool)

34092 Revert “Added –dart-flags option to flutter run” (cla: yes)