v0.34.0

• PackageConfigProvider, MockSdk, etc for improved unit testing (#2332)
  • The new PackageConfigProvider class abstracts over PackageConfig from
    package_config. PhysicalPackageConfigProvider uses the real one;
    MemoryPackageConfigProvider is used in tests.
  • The new isSdkLibraryDocumented abstracts over SdkLibrary's
    isDocumented, because it throws unimplemented for MockSdkLibrary.
  • Remove ResourceProviderExtensions.defaultSdkDir. Now this is a property
    of PackageMetaProvider.
  • Breaking change: Move io_utils listDir to be a private method in
    PackageBuilder.
  • Breaking change: Add parameter to PubPackageBuilder constructor for a
    PackageConfigProvider.
  • Breaking change: Add two parameters to the PackageMetaProvider
    constructor, one for the default SDK directory, and one for the DartSdk.
  • Deprecate package.dart's substituteNameVersion.
  • Shorten doc comments here and there to 80 columns.
  • Move any tests which use testing/test_package_small to be unit tests;
    delete the package in testing/.
  • Move some tests for properties of package which use the ginormous testing
    package to unit tests
• Add a warning when an unknown directive is parsed in a comment. (#2340)