Revert "Revert "Use native async/await support in pub.""

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
deleted file mode 100644
index d82da67d87dd3569232fcfd2d58c8bbb1c8e83f3..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/pub_generated/lib/src/barback/pub_package_provider.dart
+++ /dev/null
@@ -1,125 +0,0 @@
-// 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(() {
-      try {
-        join0() {
-          join1() {
-            var nativePath = path.fromUri(id.path);
-            var file = _graph.packages[id.package].path(nativePath);
-            _assertExists(file, id);
-            completer0.complete(new Asset.fromPath(id, file));
-          }
-          if (id.package == r'$sdk') {
-            var parts = path.split(path.fromUri(id.path));
-            assert(parts.isNotEmpty && parts[0] == 'lib');
-            parts = parts.skip(1);
-            var file = path.join(sdk.rootDirectory, path.joinAll(parts));
-            _assertExists(file, id);
-            completer0.complete(new Asset.fromPath(id, file));
-          } else {
-            join1();
-          }
-        }
-        if (id.package == r'$pub') {
-          var components = path.url.split(id.path);
-          assert(components.isNotEmpty);
-          assert(components.first == 'lib');
-          components[0] = 'dart';
-          var file = assetPath(path.joinAll(components));
-          _assertExists(file, id);
-          join2() {
-            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));
-          }
-          if (!_graph.packages.containsKey("barback")) {
-            completer0.complete(new Asset.fromPath(id, file));
-          } else {
-            join2();
-          }
-        } else {
-          join0();
-        }
-      } 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)// 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(
-              libPath,
-              recursive: true).where((file) => path.extension(file) == ".dart").map((file) {
-        var idPath =
-            path.join("lib", path.relative(file, from: sdk.rootDirectory));
-        return new AssetId('\$sdk', path.toUri(idPath).toString());
-      }));
-    } else {
-      var package = _graph.packages[packageName];
-      return new Stream.fromIterable(
-          package.listFiles(beneath: 'lib').map((file) {
-        return new AssetId(
-            packageName,
-            path.toUri(package.relative(file)).toString());
-      }));
-    }
-  }
-}