Remove unintentional dependency on analysis_server

pkg/analysis_server/test/services/correction/util_test.dart

 // Copyright (c) 2016, 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 'package:analysis_server/protocol/protocol_generated.dart';
-import 'package:analysis_server/src/services/correction/strings.dart';
 import 'package:analysis_server/src/services/correction/util.dart';
 import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer_plugin/src/utilities/string_utilities.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../../abstract_single_unit.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UtilTest);
   });
 }
@@ skipping 249 matching lines @@
   @override
   final String fullName;
 
   @override
   final Uri uri;
 
   _SourceMock(this.fullName, this.uri);
 
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }