Remove ability to disable new analysis driver

pkg/analysis_server/lib/src/server/http_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.
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:analysis_server/src/socket_server.dart';
 import 'package:analysis_server/src/status/diagnostics.dart';
 
@@ skipping 108 matching lines @@
 
       return null;
     }
   }
 
   /**
    * Handle a GET request received by the HTTP server.
    */
   Future<Null> _handleGetRequest(HttpRequest request) async {
     if (getHandler == null) {
-      if (socketServer.analysisServer.options.enableNewAnalysisDriver) {
-        getHandler = new DiagnosticsSite(socketServer, _printBuffer);
-      } else {
-        getHandler = new ErrorGetHandler(
-            'Diagnostics only supported for the new analysis driver.');
-      }
+      getHandler = new DiagnosticsSite(socketServer, _printBuffer);
     }
     await getHandler.handleGetRequest(request);
   }
 
   /**
    * Attach a listener to a newly created HTTP server.
    */
   void _handleServer(HttpServer httpServer) {
     httpServer.listen((HttpRequest request) async {
       List<String> updateValues = request.headers[HttpHeaders.UPGRADE];
@@ skipping 20 matching lines @@
    * server.
    */
   void _returnUnknownRequest(HttpRequest request) {
     HttpResponse response = request.response;
     response.statusCode = HttpStatus.NOT_FOUND;
     response.headers.contentType = ContentType.TEXT;
     response.write('Not found');
     response.close();
   }
 }