Store the async-await compiled pub code directly in the repo.

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

Index: sdk/lib/_internal/pub_generated/lib/src/barback/source_directory.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/barback/source_directory.dart b/sdk/lib/_internal/pub_generated/lib/src/barback/source_directory.dart
new file mode 100644
index 0000000000000000000000000000000000000000..14b0646a16560600398d26175843617068ab492c
--- /dev/null
+++ b/sdk/lib/_internal/pub_generated/lib/src/barback/source_directory.dart
@@ -0,0 +1,35 @@
+library pub.barback.source_directory;
+import 'dart:async';
+import 'package:watcher/watcher.dart';
+import 'asset_environment.dart';
+import 'barback_server.dart';
+class SourceDirectory {
+  final AssetEnvironment _environment;
+  final String directory;
+  final String hostname;
+  final int port;
+  Future<BarbackServer> get server => _serverCompleter.future;
+  final _serverCompleter = new Completer<BarbackServer>();
+  StreamSubscription<WatchEvent> watchSubscription;
+  SourceDirectory(this._environment, this.directory, this.hostname, this.port);
+  Future<BarbackServer> serve() {
+    return BarbackServer.bind(
+        _environment,
+        hostname,
+        port,
+        rootDirectory: directory).then((server) {
+      _serverCompleter.complete(server);
+      return server;
+    });
+  }
+  Future close() {
+    return server.then((server) {
+      var futures = [server.close()];
+      if (watchSubscription != null) {
+        var cancel = watchSubscription.cancel();
+        if (cancel != null) futures.add(cancel);
+      }
+      return Future.wait(futures);
+    });
+  }
+}