Fix a fuzzy arrow warning (dart-archive/async#41)

Closes dart-lang/async#40

Author: nex3

pkgs/async/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.0.1
+
+* Fix a fuzzy arrow type warning.
+
 ## 2.0.0
 * Remove deprecated public `result.dart` and `stream_zip.dart` libraries and
   deprecated classes `ReleaseStreamTransformer` and `CaptureStreamTransformer`.

pkgs/async/lib/src/delegate/stream_subscription.dart

@@ -10,7 +10,7 @@ import '../typed/stream_subscription.dart';
 ///
 /// Subclasses can override individual methods.
 class DelegatingStreamSubscription<T> implements StreamSubscription<T> {
-  final StreamSubscription _source;
+  final StreamSubscription<T> _source;
 
   /// Create delegating subscription forwarding calls to [sourceSubscription].
   DelegatingStreamSubscription(StreamSubscription<T> sourceSubscription)

pkgs/async/pubspec.yaml

@@ -1,5 +1,5 @@
 name: async
-version: 2.0.0
+version: 2.0.1
 author: Dart Team <[email protected]>
 description: Utility functions and classes related to the 'dart:async' library.
 homepage: https://www.github.com/dart-lang/async