Start making server strong mode clean

pkg/analysis_server/lib/src/channel/web_socket_channel.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library channel.web_socket;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 72 matching lines @@
    */
   WebSocketServerChannel(this.socket, this.instrumentationService);
 
   @override
   void close() {
     socket.close(WebSocketStatus.NORMAL_CLOSURE);
   }
 
   @override
   void listen(void onRequest(Request request),
-      {void onError(), void onDone()}) {
+      {Function onError, void onDone()}) {
     socket.listen((data) => readRequest(data, onRequest),
         onError: onError, onDone: onDone);
   }
 
   /**
    * Read a request from the given [data] and use the given function to handle
    * the request.
    */
   void readRequest(Object data, void onRequest(Request request)) {
     if (data is String) {
@@ skipping 27 matching lines @@
 
   @override
   void sendResponse(Response response) {
     ServerPerformanceStatistics.serverChannel.makeCurrentWhile(() {
       String jsonEncoding = JSON.encode(response.toJson());
       socket.add(jsonEncoding);
       instrumentationService.logResponse(jsonEncoding);
     });
   }
 }