Added a `ResultFuture` class.

lib/src/result_future.dart

Index: lib/src/result_future.dart
diff --git a/lib/src/result_future.dart b/lib/src/result_future.dart
new file mode 100644
index 0000000000000000000000000000000000000000..311e83fece833242de36dd3bfad4c473c8c3c929
--- /dev/null
+++ b/lib/src/result_future.dart
@@ -0,0 +1,35 @@
+// Copyright (c) 2015, 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 async.result_future;
+
+import 'dart:async';
+
+import '../result.dart';
+import 'delegate/future.dart';
+
+/// A [Future] wrapper that provides synchronous access to the result of the
+/// wrapped [Future] once it's completed.
+class ResultFuture<T> extends DelegatingFuture<T> {
+  /// Whether the future has fired and [result] is available.
+  bool get isComplete => result != null;
+
+  /// The result of the wrapped [Future], if it's completed.
+  ///
+  /// If it hasn't completed yet, this will be `null`.
+  Result<T> get result => _result;
+  Result<T> _result;
+
+  factory ResultFuture(Future<T> future) {
+    var resultFuture;
+    resultFuture = new ResultFuture._(Result.capture(future).then((result) {
+      resultFuture._result = result;
+      return result.asFuture;
+    }));
+    return resultFuture;
+  }
+
+  ResultFuture._(Future<T> future)
+      : super(future);
+}