Await always waits

tests/language/await_nonfuture_test.dart

+// Copyright (c) 2014, 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.
+
+// VMOptions=--enable_async --optimization-counter-threshold=5
+
+import 'package:expect/expect.dart';
+
+var X = 0;
+
+foo() async {
+  Expect.equals(X, 10);  // foo runs after main returns.
+  return await 5;
+}
+
+main() {
+  var f = foo();
+  f.then((res) => print("f completed with $res"));
+  X = 10;
+}
+