Dart: Removes need to call listen().

services/dart/test/pingpong_target/main.dart

Index: services/dart/test/pingpong_target/main.dart
diff --git a/services/dart/test/pingpong_target/main.dart b/services/dart/test/pingpong_target/main.dart
index a85e4a7b47cad98045376bed8a6fac76ac868411..a91d04022112b579c4f05582826594c4785e18bd 100644
--- a/services/dart/test/pingpong_target/main.dart
+++ b/services/dart/test/pingpong_target/main.dart
@@ -14,9 +14,8 @@ class PingPongServiceImpl implements PingPongService {
   Application _application;
   PingPongClientProxy _pingPongClient;
 
-  PingPongServiceImpl(Application application, MojoMessagePipeEndpoint endpoint)
-      : _application = application {
-    _stub = new PingPongServiceStub.fromEndpoint(endpoint, impl: this);
+  PingPongServiceImpl(this._application, MojoMessagePipeEndpoint endpoint) {
+    _stub = new PingPongServiceStub.fromEndpoint(endpoint, this);
   }
 
   void setClient(ProxyBase proxyBase) {
@@ -41,11 +40,10 @@ class PingPongApplication extends Application {
   @override
   void acceptConnection(String requestorUrl, String resolvedUrl,
       ApplicationConnection connection) {
-    connection.provideService(
-        PingPongServiceName,
+    connection.provideService(PingPongServiceName,
         (endpoint) => new PingPongServiceImpl(this, endpoint));
     // Close the application when the first connection goes down.
-    connection.listen(onClosed: close);
+    connection.onError = close;
   }
 }