adding copyright to test/test_all.dart

R=nweiz@google.com

Review URL: https://codereview.chromium.org//1041003002
diff --git a/test/test_all.dart b/test/test_all.dart
index 5a21edf..8007101 100644
--- a/test/test_all.dart
+++ b/test/test_all.dart
@@ -1,3 +1,7 @@
+// 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.
+
 import 'package:unittest/unittest.dart';
 
 import 'cascade_test.dart' as cascade;