Remove `.packages` from the Dart SDK repo

[natebosch]

I dropped a bunch of places reading this file in https://dart-review.googlesource.com/c/sdk/+/211503, but there are still some places that depend on it.

[mit-mit]

@natebosch any chance we could assign this issue to you to get the rest removed the SDK repo?

[natebosch]

Sure, I am planning to keep pushing on this as I have time.

[srawlins]

I just grepped through this repo for "dotPackages", and found references in:

• pkg/analyzer/lib/
• pkg/front_end/lib/, pkg/front_end/test/, and pkg/front_end/test_cases/
• pkg/front_end_server/test/
• pkg/vm/bin/kernel_service.dart
• tests/lib/isolate/, tests/lib_2/isolate/

[natebosch]

I just grepped through this repo for "dotPackages"

Yeah there are still a bunch. Any help cleaning up whatever you find is great.

dotPackages as a variable name can sometimes refer to the path to .dart_tool/package_config.json since some tools were updated to understand either file with the same argument.

[scheglov]

There are a few shared tests that use .packages, started failing here.

standalone_2/package/scenarios/both_dir_and_file/prefers_packages_file_test
standalone_2/package/scenarios/packages_file_in_parent/sub/packages_file_in_parent_test
standalone_2/package/scenarios/packages_file_only/packages_file_only_test

[mit-mit]

@sigmundch there are a bunch of search hits on .packages in /pkg/compiler/ & /pkg/dev_compiler/ -- is that something the web team can look at in Q2?

[mit-mit]

@johnniwinther there are a bunch of search hits on .packages in /pkg/front_end/ -- is that something the CFE team can look at in Q2?