Remove the unused class SingleContextManager

pkg/analysis_server/lib/src/server/driver.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 'dart:math';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
@@ skipping 289 matching lines @@
    */
   ResolverProvider fileResolverProvider;
 
   /**
    * The package resolver provider used to override the way package URI's are
    * resolved in some contexts.
    */
   ResolverProvider packageResolverProvider;
 
   /**
-   * If this flag is `true`, then single analysis context should be used for
-   * analysis of multiple analysis roots, special files that could otherwise
-   * cause creating additional contexts, such as `pubspec.yaml`, or `.packages`,
-   * or analysis options are ignored.
-   */
-  bool useSingleContextManager = false;
-
-  /**
    * The plugins that are defined outside the analysis_server package.
    */
   List<Plugin> _userDefinedPlugins = <Plugin>[];
 
   SocketServer socketServer;
 
   HttpAnalysisServer httpServer;
 
   StdioAnalysisServer stdioServer;
 
@@ skipping 118 matching lines @@
     // Create the sockets and start listening for requests.
     //
     socketServer = new SocketServer(
         analysisServerOptions,
         new DartSdkManager(defaultSdkPath, true),
         defaultSdk,
         instrumentationService,
         diagnosticServer,
         serverPlugin,
         fileResolverProvider,
-        packageResolverProvider,
-        useSingleContextManager);
+        packageResolverProvider);
     httpServer = new HttpAnalysisServer(socketServer);
     stdioServer = new StdioAnalysisServer(socketServer);
     socketServer.userDefinedPlugins = _userDefinedPlugins;
 
     diagnosticServer.httpServer = httpServer;
     if (serve_http) {
       diagnosticServer.startOnPort(port);
     }
 
     _captureExceptions(instrumentationService, () {
@@ skipping 178 matching lines @@
 
   _DiagnosticServerImpl();
 
   @override
   Future<int> getServerPort() => httpServer.serveHttp();
 
   Future startOnPort(int port) {
     return httpServer.serveHttp(port);
   }
 }