Make VM event streams look like real dart streams.

runtime/observatory/tests/service/debugger_location_test.dart

Index: runtime/observatory/tests/service/debugger_location_test.dart
diff --git a/runtime/observatory/tests/service/debugger_location_test.dart b/runtime/observatory/tests/service/debugger_location_test.dart
index 7c4de5b8699e922db617ab497b224fa71f4b7ee6..e1e15c8d5dc40d726be82d27ca803810c2046c21 100644
--- a/runtime/observatory/tests/service/debugger_location_test.dart
+++ b/runtime/observatory/tests/service/debugger_location_test.dart
@@ -56,10 +56,14 @@ var tests = [
   return isolate.rootLibrary.load().then((_) {
       // Listen for breakpoint event.
       Completer completer = new Completer();
-      isolate.vm.events.stream.listen((ServiceEvent event) {
-        if (event.kind == ServiceEvent.kPauseBreakpoint) {
-          completer.complete();
-        }
+      isolate.vm.getEventStream(VM.kDebugStream).then((stream) {
+        var subscription;
+        subscription = stream.listen((ServiceEvent event) {
+          if (event.kind == ServiceEvent.kPauseBreakpoint) {
+            subscription.cancel();
+            completer.complete();
+          }
+        });
       });
 
       // Add the breakpoint.