Make the Dart application library code stop using the "wrong way" service provider (a.k.a. exposed_…

mojo/dart/apptests/test_apps/pingpong/lib/main.dart

Index: mojo/dart/apptests/test_apps/pingpong/lib/main.dart
diff --git a/mojo/dart/apptests/test_apps/pingpong/lib/main.dart b/mojo/dart/apptests/test_apps/pingpong/lib/main.dart
index 1e0ff6f3bb51e25b2612c2f383120e75244022d8..5a3a695c318a2093fb9a96e57dd3437fe1fa43c7 100644
--- a/mojo/dart/apptests/test_apps/pingpong/lib/main.dart
+++ b/mojo/dart/apptests/test_apps/pingpong/lib/main.dart
@@ -126,9 +126,6 @@ class PingPongApplication extends Application {
   @override
   void acceptConnection(String requestorUrl, String resolvedUrl,
       ApplicationConnection connection) {
-    // No services are required from the remote end.
-    connection.remoteServiceProvider.close();
-
     connection.provideService(PingPongService.serviceName,
         (endpoint) => new PingPongServiceImpl(this, endpoint),
         description: PingPongServiceStub.serviceDescription);