Make VM event streams look like real dart streams.

runtime/observatory/tests/service/evaluate_activation_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=--compile-all --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:math' as math;
@@ skipping 60 matching lines @@
   // silence analyzer.
   expect(math.sqrt(4), equals(2));
   Library rootLib = await isolate.rootLibrary.load();
   ServiceFunction function =
       rootLib.functions.singleWhere((f) => f.name == 'breakHere');
   Breakpoint bpt = await isolate.addBreakpointAtEntry(function);
   print("Breakpoint: $bpt");
   expect(bpt is Breakpoint, isTrue);  // I.e, not null.
 
   bool hitBreakpoint = false;
+  var stream = await isolate.vm.getDebugEventStream();
   var sub;
-  sub = isolate.vm.events.stream.listen((ServiceEvent event) async {
+  sub = stream.listen((ServiceEvent event) async {
     print("Event $event");
     if (event.kind == ServiceEvent.kPauseBreakpoint) {
       var frameNumber = 1, r;
       r = await isolate.evalFrame(frameNumber, '123');  /// instance: ok
       expect(r.valueAsString, equals('123'));  /// instance: continued
       r = await isolate.evalFrame(frameNumber, 'this');  /// scope: ok
       expect(r.clazz.name, equals('C'));  /// scope: continued
       r = await isolate.evalFrame(frameNumber, 'instVar');  /// instance: continued
       expect(r.valueAsString, equals('1'));  /// instance: continued
       r = await isolate.evalFrame(frameNumber, 'classVar'); /// instance: continued
@@ skipping 26 matching lines @@
 
 testMethod2(Isolate isolate) async {
   Library rootLib = await isolate.rootLibrary.load();
   ServiceFunction function =
       rootLib.functions.singleWhere((f) => f.name == 'breakHere');
   Breakpoint bpt = await isolate.addBreakpointAtEntry(function);
   print("Breakpoint: $bpt");
   expect(bpt is Breakpoint, isTrue);  // I.e, not null.
 
   bool hitBreakpoint = false;
+  var stream = await isolate.vm.getDebugEventStream();
   var sub;
-  sub = isolate.vm.events.stream.listen((ServiceEvent event) async {
+  sub = stream.listen((ServiceEvent event) async {
     print("Event $event");
     if (event.kind == ServiceEvent.kPauseBreakpoint) {
       var frameNumber = 1, r;
       r = await isolate.evalFrame(frameNumber, '123');
       expect(r.valueAsString, equals('123'));
       r = await isolate.evalFrame(frameNumber, 'this');
       expect(r is DartError, isTrue);
       r = await isolate.evalFrame(frameNumber, 'instVar');
       expect(r is DartError, isTrue);
       r = await isolate.evalFrame(frameNumber, 'classVar');
@@ skipping 26 matching lines @@
 
 testMethod3(Isolate isolate) async {
   Library rootLib = await isolate.rootLibrary.load();
   ServiceFunction function =
       rootLib.functions.singleWhere((f) => f.name == 'breakHere');
   Breakpoint bpt = await isolate.addBreakpointAtEntry(function);
   print("Breakpoint: $bpt");
   expect(bpt is Breakpoint, isTrue);  // I.e, not null.
 
   bool hitBreakpoint = false;
+  var stream = await isolate.vm.getDebugEventStream();
   var sub;
-  sub = isolate.vm.events.stream.listen((ServiceEvent event) async {
+  sub = stream.listen((ServiceEvent event) async {
     print("Event $event");
     if (event.kind == ServiceEvent.kPauseBreakpoint) {
       var frameNumber = 1, r;
       r = await isolate.evalFrame(frameNumber, '123');
       expect(r.valueAsString, equals('123'));
       r = await isolate.evalFrame(frameNumber, 'this');
       expect(r.clazz.name, equals('C'));
       r = await isolate.evalFrame(frameNumber, 'instVar');
       expect(r.valueAsString, equals('1'));
       r = await isolate.evalFrame(frameNumber, 'classVar');
@@ skipping 19 matching lines @@
 
 testMethod4(Isolate isolate) async {
   Library rootLib = await isolate.rootLibrary.load();
   ServiceFunction function =
       rootLib.functions.singleWhere((f) => f.name == 'breakHere');
   Breakpoint bpt = await isolate.addBreakpointAtEntry(function);
   print("Breakpoint: $bpt");
   expect(bpt is Breakpoint, isTrue);  // I.e, not null.
 
   bool hitBreakpoint = false;
+  var stream = await isolate.vm.getDebugEventStream();
   var sub;
-  sub = isolate.vm.events.stream.listen((ServiceEvent event) async {
+  sub = stream.listen((ServiceEvent event) async {
     print("Event $event");
     if (event.kind == ServiceEvent.kPauseBreakpoint) {
       var frameNumber = 1, r;
       r = await isolate.evalFrame(frameNumber, '123');  /// instance: continued
       expect(r.valueAsString, equals('123'));  /// instance: continued
       r = await isolate.evalFrame(frameNumber, 'this');  /// scope: continued
       expect(r.clazz.name, equals('C'));  /// scope: continued
       r = await isolate.evalFrame(frameNumber, 'instVar');  /// instance: continued
       expect(r.valueAsString, equals('1'));  /// instance: continued
       r = await isolate.evalFrame(frameNumber, 'classVar');  /// instance: continued
@@ skipping 26 matching lines @@
 }
 
 var tests = [
   testMethod,
   testMethod2,
   testMethod3,
   testMethod4,
 ];
 
 main(args) => runIsolateTests(args, tests);