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
new file mode 100644
index 0000000000000000000000000000000000000000..d82da67d87dd3569232fcfd2d58c8bbb1c8e83f3
--- /dev/null
+++ b/sdk/lib/_internal/pub_generated/lib/src/barback/pub_package_provider.dart
@@ -0,0 +1,125 @@
+// 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());
+      }));
+    }
+  }
+}