Centralized event streams

runtime/observatory/tests/service/debugger_inspect_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';
 import 'dart:async';
 import 'dart:developer';
 
 class Point {
   int x, y;
   Point(this.x, this.y);
 }
 
 void testeeDo() {
   inspect(new Point(3, 4));
 }
 
 var tests = [
 
 (Isolate isolate) async {
   Completer completer = new Completer();
   var stream = await isolate.vm.getEventStream(VM.kDebugStream);
   var subscription;
   subscription = stream.listen((ServiceEvent event) {
     if (event.kind == ServiceEvent.kInspect) {
-      expect((event.inspectee as Instance).clazz.name, equals('Point'));
+      expect(event.inspectee.clazz.name, equals('Point'));
       subscription.cancel();
       completer.complete();
     }
   });
 
   // Start listening for events first.
   await isolate.rootLibrary.evaluate('testeeDo();');
   return completer.future;
 },
 
 ];
 
 main(args) => runIsolateTests(args, tests);