Use .packages instead of pubspec.yaml

pkg/dev_compiler/pubspec.yaml

-name: dev_compiler
-version: 0.2.0
-description: >
-  Experimental Dart to JavaScript compiler designed to create idiomatic,
-  readable JavaScript output.
-
-author: Dart Dev Compiler team <dev-compiler@dartlang.org>
-homepage: https://github.com/dart-lang/dev_compiler
-
-dependencies:
-  analyzer: ^0.29.0-alpha.0
-  args: ^0.13.0
-  bazel_worker: ^0.1.0
-  browser: ^0.10.0
-  cli_util: ^0.0.1
-  func: ^0.1.0
-  html: ^0.12.0
-  js: ^0.6.0
-  meta: ^1.0.3
-  path: ^1.3.0
-  pub_semver: ^1.1.0
-  source_maps: ^0.10.0
-  source_span: ^1.0.2
-
-dev_dependencies:
-  # We pin a specific version to ensure everyone is formatting the code exactly
-  # the same way. This is because any change in dart_style, even non-breaking
-  # changes, may change the output format.
-  dart_style: 0.2.4
-  test: ^0.12.0
-  unittest: ^0.11.6
-  webdriver: ^1.1.0
-
-dependency_overrides:
-  # Depend directly on packages in the same repositiory
-  analyzer: { path: ../analyzer }
-  meta: { path: ../meta }
-
-environment:
-  sdk: ">=1.12.0 <2.0.0"