Unify the server and plugin versions of the generators

pkg/analysis_server/test/services/completion/dart/combinator_contributor_test.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.services.completion.dart.combinator;
-
-import 'package:analysis_server/plugin/protocol/protocol.dart';
+import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
 import 'package:analysis_server/src/services/completion/dart/combinator_contributor.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'completion_contributor_util.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CombinatorContributorTest);
@@ skipping 137 matching lines @@
     assertSuggestTopLevelVar('PI', 'double',
         kind: CompletionSuggestionKind.IDENTIFIER);
   }
 }
 
 @reflectiveTest
 class CombinatorContributorTest_Driver extends CombinatorContributorTest {
   @override
   bool get enableNewAnalysisDriver => true;
 }