Async-step, first cut.

runtime/observatory/tests/service/test_helper.dart

Index: runtime/observatory/tests/service/test_helper.dart
diff --git a/runtime/observatory/tests/service/test_helper.dart b/runtime/observatory/tests/service/test_helper.dart
index 8ff0b253878d157626367658ccfcfb9ce534a2cc..7016fb66027fe2f8d894915c8b87908ebe169dce 100644
--- a/runtime/observatory/tests/service/test_helper.dart
+++ b/runtime/observatory/tests/service/test_helper.dart
@@ -155,26 +155,35 @@ Future processServiceEvents(VM vm,
 }
 
 
-Future<Isolate> hasStoppedAtBreakpoint(Isolate isolate) async {
-  await isolate.reload();  // Might have missed pauseEvent.
-
-  if ((isolate.pauseEvent != null) &&
-      (isolate.pauseEvent.kind == ServiceEvent.kPauseBreakpoint)) {
-    // Already waiting at a breakpoint.
-    print('Breakpoint reached');
-    return new Future.value(isolate);
-  }
-
+Future<Isolate> hasStoppedAtBreakpoint(Isolate isolate) {

[Cutch, 2015/07/15 17:04:23]

why remove async?
why switch from using await to using then()?

   // Set up a listener to wait for breakpoint events.
   Completer completer = new Completer();
   isolate.vm.getEventStream(VM.kDebugStream).then((stream) {
     var subscription;
     subscription = stream.listen((ServiceEvent event) {
+        print("Event: $event");
         if (event.kind == ServiceEvent.kPauseBreakpoint) {
           print('Breakpoint reached');
           subscription.cancel();
-          completer.complete();
+          if (completer != null) {
+            completer.complete(isolate);
+            completer = null;
+          }
+        }
+    });
+
+    // Pause may have happened before we subscribed.
+    isolate.reload().then((_) {
+      if ((isolate.pauseEvent != null) &&
+         (isolate.pauseEvent.kind == ServiceEvent.kPauseBreakpoint)) {
+        // Already waiting at a breakpoint.
+        print('Breakpoint reached');
+        subscription.cancel();
+        if (completer != null) {
+          completer.complete(isolate);
+          completer = null;
         }
+      }
     });
   });