Fix CancelableOperation.valueOrCancellation's type signature (#68)

* Fix CancelableOperation.valueOrCancellation's type signature

* Increment minor version, add changelog entry
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 649b5a1..c71ac91 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 2.1.0
+
+* Fix `CancelableOperation.valueOrCancellation`'s type signature
+
 ## 2.0.8
 
 * Set max SDK version to `<3.0.0`.
diff --git a/lib/src/cancelable_operation.dart b/lib/src/cancelable_operation.dart
index 2bf0f3b..0e010da 100644
--- a/lib/src/cancelable_operation.dart
+++ b/lib/src/cancelable_operation.dart
@@ -63,7 +63,7 @@
   /// If this operation completes, this completes to the same result as [value].
   /// If this operation is cancelled, the returned future waits for the future
   /// returned by [cancel], then completes to [cancellationValue].
-  Future valueOrCancellation([T cancellationValue]) {
+  Future<T> valueOrCancellation([T cancellationValue]) {
     var completer = new Completer<T>.sync();
     value.then((result) => completer.complete(result),
         onError: completer.completeError);
diff --git a/pubspec.yaml b/pubspec.yaml
index 582663a..37db660 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: async
-version: 2.0.9-dev
+version: 2.1.0
 
 description: Utility functions and classes related to the 'dart:async' library.
 author: Dart Team <misc@dartlang.org>