Fix get_cpu_profile_timeline_rpc_test.

runtime/observatory/tests/service/get_cpu_profile_timeline_rpc_test.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.
 // VMOptions=--error_on_bad_type --error_on_bad_override
 
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 
 import 'test_helper.dart';
 
@@ skipping 13 matching lines @@
   (Isolate isolate) async {
     var params = {
       'tags': 'VMUser'
     };
     var result = await isolate.invokeRpcNoUpgrade(
         '_getCpuProfileTimeline', params);
     print(result);
     expect(result['type'], equals('_CpuProfileTimeline'));
 
     var isString = new isInstanceOf<String>();
+    var isInt = new isInstanceOf<int>();
 
     Map frames = result['stackFrames'];
     for (Map frame in frames.values) {
       expect(frame['category'], isString);
       expect(frame['name'], isString);
       if (frame['parent'] != null) {
         expect(frames.containsKey(frame['parent']), isTrue);
       }
     }
 
     List events = result['traceEvents'];
     for (Map event in events) {
       expect(event['ph'], equals('P'));
-      expect(event['pid'], isString);
-      expect(event['tid'], isString);
-      expect(event['ts'], isString);
+      expect(event['pid'], isInt);
+      expect(event['tid'], isInt);
+      expect(event['ts'], isInt);
       expect(event['category'], equals("Dart"));
       expect(frames.containsKey(event['sf']), isTrue);
     }
   },
 ];
 
 main(args) async => runIsolateTests(args, tests, testeeBefore: testeeDo);