Regenerate pub sources.

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

Index: sdk/lib/_internal/pub_generated/lib/src/barback/pub_package_provider.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/barback/pub_package_provider.dart b/sdk/lib/_internal/pub_generated/lib/src/barback/pub_package_provider.dart
index 77807e755189c228576f7e6297ccc432b34c165f..d82da67d87dd3569232fcfd2d58c8bbb1c8e83f3 100644
--- a/sdk/lib/_internal/pub_generated/lib/src/barback/pub_package_provider.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/barback/pub_package_provider.dart
@@ -1,22 +1,35 @@
+// 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.pub_package_provider;
+
 import 'dart:async';
+
 import 'package:barback/barback.dart';
 import 'package:path/path.dart' as path;
+
 import '../io.dart';
 import '../package_graph.dart';
 import '../preprocess.dart';
 import '../sdk.dart' as sdk;
 import '../utils.dart';
+
+/// An implementation of barback's [PackageProvider] interface so that barback
+/// can find assets within pub packages.
 class PubPackageProvider implements StaticPackageProvider {
   final PackageGraph _graph;
   final List<String> staticPackages;
+
   Iterable<String> get packages =>
       _graph.packages.keys.toSet().difference(staticPackages.toSet());
+
   PubPackageProvider(PackageGraph graph)
       : _graph = graph,
         staticPackages = [
           r"$pub",
           r"$sdk"]..addAll(graph.packages.keys.where(graph.isPackageStatic));
+
   Future<Asset> getAsset(AssetId id) {
     final completer0 = new Completer();
     scheduleMicrotask(() {
@@ -47,8 +60,9 @@ class PubPackageProvider implements StaticPackageProvider {
           var file = assetPath(path.joinAll(components));
           _assertExists(file, id);
           join2() {
-            var versions =
-                mapMap(_graph.packages, value: ((_, package) => package.version));
+            var versions = mapMap(_graph.packages, value: ((_, package) {
+              return package.version;
+            }));
             var contents = readTextFile(file);
             contents = preprocess(contents, versions, path.toUri(file));
             completer0.complete(new Asset.fromString(id, contents));
@@ -61,27 +75,34 @@ class PubPackageProvider implements StaticPackageProvider {
         } else {
           join0();
         }
-      } catch (e0) {
-        completer0.completeError(e0);
+      } catch (e, s) {
+        completer0.completeError(e, s);
       }
     });
     return completer0.future;
   }
+
+  /// Throw an [AssetNotFoundException] for [id] if [path] doesn't exist.
   void _assertExists(String path, AssetId id) {
     if (!fileExists(path)) throw new AssetNotFoundException(id);
   }
+
   Stream<AssetId> getAllAssetIds(String packageName) {
     if (packageName == r'$pub') {
+      // "$pub" is a pseudo-package that allows pub's transformer-loading
+      // infrastructure to share code with pub proper. We provide it only during
+      // the initial transformer loading process.
       var dartPath = assetPath('dart');
       return new Stream.fromIterable(
-          listDir(
-              dartPath,
-              recursive: true).where(
-                  (file) => path.extension(file) == ".dart").map((library) {
+          listDir(dartPath, recursive: true)// Don't include directories.
+      .where((file) => path.extension(file) == ".dart").map((library) {
         var idPath = path.join('lib', path.relative(library, from: dartPath));
         return new AssetId('\$pub', path.toUri(idPath).toString());
       }));
     } else if (packageName == r'$sdk') {
+      // "$sdk" is a pseudo-package that allows the dart2js transformer to find
+      // the Dart core libraries without hitting the file system directly. This
+      // ensures they work with source maps.
       var libPath = path.join(sdk.rootDirectory, "lib");
       return new Stream.fromIterable(
           listDir(