Make more use of generated code in analysis server.

pkg/analysis_server/lib/src/socket_server.dart

Index: pkg/analysis_server/lib/src/socket_server.dart
diff --git a/pkg/analysis_server/lib/src/socket_server.dart b/pkg/analysis_server/lib/src/socket_server.dart
index a18a0da43ee836ba12421729eb0c598cd298dcfe..9623ae40201c5a125f3727ca0e34b2dd58922b18 100644
--- a/pkg/analysis_server/lib/src/socket_server.dart
+++ b/pkg/analysis_server/lib/src/socket_server.dart
@@ -53,9 +53,9 @@ class SocketServer {
   void createAnalysisServer(ServerCommunicationChannel serverChannel) {
     if (analysisServer != null) {
       RequestError error = new RequestError.serverAlreadyStarted();
-      serverChannel.sendResponse(new Response('', error));
+      serverChannel.sendResponse(new Response('', error: error));
       serverChannel.listen((Request request) {
-        serverChannel.sendResponse(new Response(request.id, error));
+        serverChannel.sendResponse(new Response(request.id, error: error));
       });
       return;
     }