Maintains functionality of existing '--write-X-uri' and '--read-X-uri' but also introduces new '--stage' flag that indicates which phases of the compiler should run.
Also expands the behavior of the `--output` flag to support taking a file prefix and/or an output directory that files are written out to.
Valid invocations can look like:
`dart2js main.dart --stage=cfe`
`dart2js main.dart --stage=cfe --output=prefix1-`
`dart2js main.dart --stage=cfe --output=/some/path/`
Change-Id: If90fb16f549d35f16f77d660c51f8d28673e454f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/300520
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Mayank Patke <fishythefish@google.com>
Commit-Queue: Nate Biggs <natebiggs@google.com>
Nate Biggs
776b614018