Use AnalysisServer.running only to track whether server has been shut down.

pkg/analysis_server/lib/src/socket_server.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 socket.server;
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/channel.dart';
 import 'package:analysis_server/src/domain_context.dart';
 import 'package:analysis_server/src/domain_server.dart';
@@ skipping 20 matching lines @@
     if (analysisServer != null) {
       var error = new RequestError.serverAlreadyStarted();
       serverChannel.sendResponse(new Response('', error));
       serverChannel.listen((Request request) {
         serverChannel.sendResponse(new Response(request.id, error));
       });
       return;
     }
     analysisServer = new AnalysisServer(serverChannel);
     _initializeHandlers(analysisServer);
-    analysisServer.run();
   }
 
   /**
    * Initialize the handlers to be used by the given [server].
    */
   void _initializeHandlers(AnalysisServer server) {
     server.handlers = [
         new ServerDomainHandler(server),
         new ContextDomainHandler(server),
     ];
   }
 
 }