Use different SDKs based on option settings

pkg/analysis_server/test/analysis_abstract.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 test.domain.analysis.abstract;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/analysis_server.dart';
@@ skipping 108 matching lines @@
     //
     // Create server
     //
     return new AnalysisServer(
         serverChannel,
         resourceProvider,
         packageMapProvider,
         index,
         serverPlugin,
         new AnalysisServerOptions(),
-        new MockSdk(),
+        () => new MockSdk(),
         InstrumentationService.NULL_SERVICE);
   }
 
   Index createIndex() {
     return null;
   }
 
   /**
    * Creates a project `/project`.
    */
@@ skipping 87 matching lines @@
   }
 
   /**
    * Completes with a successful [Response] for the given [request].
    * Otherwise fails.
    */
   Future<Response> waitResponse(Request request) async {
     return serverChannel.sendRequest(request);
   }
 }