Regenerate pub sources.

sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart

Index: sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart b/sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart
index cf8e16f26f23b8da64ebb231b7bd29daa44b256e..2017d9bb0a8cd6305545b51cc37836e8dfb880a9 100644
--- a/sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart
@@ -1,24 +1,63 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
 library pub.barback.transformer_id;
+
 import 'dart:async';
+
 import 'package:barback/barback.dart';
 import 'package:source_span/source_span.dart';
+
 import '../utils.dart';
+
+/// A list of the names of all built-in transformers that pub exposes.
 const _BUILT_IN_TRANSFORMERS = const ['\$dart2js'];
+
+/// An identifier that indicates the library that contains a transformer.
+///
+/// It's possible that the library identified by [this] defines multiple
+/// transformers. If so, they're all always loaded in the same phase.
 class TransformerId {
+  /// The package containing the library where the transformer is defined.
   final String package;
+
+  /// The `/`-separated path to the library that contains this transformer.
+  ///
+  /// This is relative to the `lib/` directory in [package], and doesn't end in
+  /// `.dart`.
+  ///
+  /// This can be null; if so, it indicates that the transformer(s) should be
+  /// loaded from `lib/transformer.dart` if that exists, and `lib/$package.dart`
+  /// otherwise.
   final String path;
+
+  /// The source span from which this id was parsed.
   final SourceSpan span;
+
+  /// Whether this ID points to a built-in transformer exposed by pub.
   bool get isBuiltInTransformer => package.startsWith('\$');
+
+  /// Parses a transformer identifier.
+  ///
+  /// A transformer identifier is a string of the form "package_name" or
+  /// "package_name/path/to/library". It does not have a trailing extension. If
+  /// it just has a package name, it expands to lib/transformer.dart if that
+  /// exists, or lib/${package}.dart otherwise. Otherwise, it expands to
+  /// lib/${path}.dart. In either case it's located in the given package.
   factory TransformerId.parse(String identifier, SourceSpan span) {
     if (identifier.isEmpty) {
       throw new FormatException('Invalid library identifier: "".');
     }
+
     var parts = split1(identifier, "/");
     if (parts.length == 1) {
       return new TransformerId(parts.single, null, span);
     }
+
     return new TransformerId(parts.first, parts.last, span);
   }
+
   TransformerId(this.package, this.path, this.span) {
     if (!package.startsWith('\$')) return;
     if (_BUILT_IN_TRANSFORMERS.contains(package)) return;
@@ -26,15 +65,29 @@ class TransformerId {
         'Unsupported built-in transformer $package.',
         span);
   }
+
   bool operator ==(other) =>
       other is TransformerId && other.package == package && other.path == path;
+
   int get hashCode => package.hashCode ^ path.hashCode;
+
+  /// Returns a serialized form of [this] that can be passed to
+  /// [new TransformerId.parse].
   String serialize() => path == null ? package : '$package/$path';
+
   String toString() => serialize();
+
+  /// Returns the asset id for the library identified by this transformer id.
+  ///
+  /// If `path` is null, this will determine which library to load. Unlike
+  /// [getAssetId], this doesn't take generated assets into account; it's used
+  /// to determine transformers' dependencies, which requires looking at files
+  /// on disk.
   Future<AssetId> getAssetId(Barback barback) {
     if (path != null) {
       return new Future.value(new AssetId(package, 'lib/$path.dart'));
     }
+
     var transformerAsset = new AssetId(package, 'lib/transformer.dart');
     return barback.getAssetById(
         transformerAsset).then(