Move the wire protocol support into the public API

pkg/analysis_server/test/services/completion/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/src/protocol.dart';
+import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/services/completion/combinator_contributor.dart';
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../../utils.dart';
 import 'completion_test_util.dart';
 
 main() {
   initializeTestEnvironment();
   defineReflectiveTests(CombinatorContributorTest);
@@ skipping 114 matching lines @@
           kind: CompletionSuggestionKind.IDENTIFIER);
       assertSuggestFunctionTypeAlias('F2', null, false, DART_RELEVANCE_DEFAULT,
           CompletionSuggestionKind.IDENTIFIER);
       assertNotSuggested('C');
       assertNotSuggested('D');
       assertNotSuggested('X');
       assertNotSuggested('Object');
     });
   }
 }