[dart:io] Adds Platform.operatingSystemVersion

tests/standalone/io/platform_os_version_test.dart

Index: tests/standalone/io/platform_os_version_test.dart
diff --git a/tests/standalone/io/platform_os_version_test.dart b/tests/standalone/io/platform_os_version_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..ee276aabddbc9165de76ac47a1ef006bef17e91a
--- /dev/null
+++ b/tests/standalone/io/platform_os_version_test.dart
@@ -0,0 +1,14 @@
+// Copyright (c) 2017, 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 "dart:io";
+
+import "package:expect/expect.dart";
+
+main() {
+  var version = Platform.operatingSystemVersion;
+  Expect.isNotNull(version);
+  Expect.isTrue(version is String);
+  print(Platform.operatingSystemVersion);
+}