[CP] Fix dart run missing fast path when using Flutter #55758
Description
Commit(s) to merge
dart-lang/pub@e70850b
Rolled to the sdk in: https://dart-review.googlesource.com/c/sdk/+/367024?tab=checks
Target
stable
Prepared changelist for beta/stable
https://dart-review.googlesource.com/c/sdk/+/367060
Issue Description
Without this it is hard/impossible to use build_runner together with localization on flutter.
dart run build_runner build would wrongly think that the current resolution is stale, and redo it. Missing the flutter_gen package that flutter pub get injects to the package config.
This is a regression that was introduced in: dart-lang/pub#4160 rolled to the sdk in 74c94ee
What is the fix
By fixing the fast-path check, we will not replace the package_config if it is up-to-date.
This does not fix the underlying problem that dart run doesn't inject the flutter_gen package when the resolution is stale, but at least makes it possible to run build_runner when localization is enabled.
Why cherry-pick
To fix the regression
Risk
Medium-low
Issue link(s)
Extra Info
No response