Modernize the package's style.

lib/async.dart

Index: lib/async.dart
diff --git a/lib/async.dart b/lib/async.dart
index ef1ac04fc4e5311f3eb3a61bc36edb17a7c6d416..84f849e35dec10d2644ad9d850ce7a08dcc8a85b 100644
--- a/lib/async.dart
+++ b/lib/async.dart
@@ -2,9 +2,6 @@
 // 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 dart.pkg.async;
-
-export "result.dart";
 export "src/async_memoizer.dart";
 export "src/cancelable_operation.dart";
 export "src/delegate/event_sink.dart";
@@ -17,7 +14,12 @@ export "src/future_group.dart";
 export "src/lazy_stream.dart";
 export "src/null_stream_sink.dart";
 export "src/restartable_timer.dart";
-export "src/result_future.dart";
+export "src/result.dart";
+export "src/result/capture_transformer.dart";
+export "src/result/error.dart";
+export "src/result/future.dart";
+export "src/result/release_transformer.dart";
+export "src/result/value.dart";
 export "src/single_subscription_transformer.dart";
 export "src/stream_completer.dart";
 export "src/stream_group.dart";