Support an @OnPlatform annotation.

lib/src/backend/suite.dart

 // 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 test.backend.suite;
 
 import 'dart:collection';
 
 import 'metadata.dart';
 import 'operating_system.dart';
@@ skipping 26 matching lines @@
   ///
   /// This filters out tests that are invalid for [platform] and [os] and
   /// resolves platform-specific metadata. If the suite itself is invalid for
   /// [platform] and [os], returns `null`.
   Suite forPlatform(TestPlatform platform, {OperatingSystem os}) {
     if (!metadata.testOn.evaluate(platform, os: os)) return null;
     return change(tests: tests.where((test) {
       return test.metadata.testOn.evaluate(platform, os: os);
     }).map((test) {
       return test.change(metadata: test.metadata.forPlatform(platform, os: os));
-    }));
+    }), metadata: metadata.forPlatform(platform, os: os));
   }
 
   /// Returns a new suite with the given fields updated.
   Suite change({String path, String platform, Metadata metadata,
       Iterable<Test> tests}) {
     if (path == null) path = this.path;
     if (platform == null) platform = this.platform;
     if (metadata == null) metadata = this.metadata;
     if (tests == null) tests = this.tests;
     return new Suite(tests, path: path, platform: platform, metadata: metadata);
   }
 }