Make VM event streams look like real dart streams.

runtime/observatory/tests/service/coverage_test.dart

Index: runtime/observatory/tests/service/coverage_test.dart
diff --git a/runtime/observatory/tests/service/coverage_test.dart b/runtime/observatory/tests/service/coverage_test.dart
index 45a60a8a9ac669ce80c9a6a290adabf91c00cc91..9f69984f834197f8dfd6e18d48e0cf62065ea7fb 100644
--- a/runtime/observatory/tests/service/coverage_test.dart
+++ b/runtime/observatory/tests/service/coverage_test.dart
@@ -57,11 +57,15 @@ var tests = [
   return isolate.rootLibrary.load().then((_) {
       // Set up a listener to wait for breakpoint events.
       Completer completer = new Completer();
-      isolate.vm.events.stream.listen((ServiceEvent event) {
-        if (event.kind == ServiceEvent.kPauseBreakpoint) {
-          print('Breakpoint reached');
-          completer.complete();
-        }
+      isolate.vm.getDebugEventStream().then((stream) {
+        var subscription;
+        subscription = stream.listen((ServiceEvent event) {
+          if (event.kind == ServiceEvent.kPauseBreakpoint) {
+            print('Breakpoint reached');
+            completer.complete();
+            subscription.cancel();
+          }
+        });
       });
 
       // Create a timer to set a breakpoint with a short delay.