* Upgrade everything except matcher.
* Roll matcher (and test)
* Adjust tests that depend on flutter:test directly to depend on a shim
* Require use of package:test shim and remove other references to package:test
* Add `--dry-run` option to `flutter format` sub command
* Add `--set-exit-if-changed` option to `format` sub command
* Add `--machine` option to `format` sub command
* Make variable names to be not shorthand: cmd -> command
Fix https://github.com/flutter/flutter/pull/18360#discussion_r199656120