Mark analysis_server as being strong-mode clean

pkg/analysis_server/lib/src/channel/byte_stream_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.byte_stream;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 33 matching lines @@
         .transform(new NotificationConverter())
         .asBroadcastStream();
   }
 
   @override
   Future close() {
     return output.close();
   }
 
   @override
-  Future<Response> sendRequest(Request request) {
+  Future<Response> sendRequest(Request request) async {
     String id = request.id;
     output.write(JSON.encode(request.toJson()) + '\n');
-    return responseStream.firstWhere((Response response) => response.id == id);
+    return await responseStream
+        .firstWhere((Response response) => response.id == id);
   }
 }
 
 /**
  * Instances of the class [ByteStreamServerChannel] implement a
  * [ServerCommunicationChannel] that uses a stream and a sink (typically,
  * standard input and standard output) to communicate with clients.
  */
 class ByteStreamServerChannel implements ServerCommunicationChannel {
   final Stream _input;
@@ skipping 95 matching lines @@
       // structure as a request.
       Request request = new Request.fromString(data);
       if (request == null) {
         sendResponse(new Response.invalidRequestFormat());
         return;
       }
       onRequest(request);
     });
   }
 }