Re-apply change to move to plugin package

pkg/analysis_server/test/edit/format_test.dart

 // Copyright (c) 2015, 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.edit.format;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/edit/edit_domain.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:analysis_server/src/protocol.dart';
-import 'package:analyzer/src/plugin/plugin_impl.dart';
+import 'package:plugin/manager.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:unittest/unittest.dart' hide ERROR;
 
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
 main() {
   groupSep = ' | ';
   defineReflectiveTests(FormatTest);
 }
@@ skipping 76 matching lines @@
     });
   }
 
   EditFormatResult _formatAt(int selectionOffset, int selectionLength) {
     Request request = new EditFormatParams(
         testFile, selectionOffset, selectionLength).toRequest('0');
     Response response = handleSuccessfulRequest(request);
     return new EditFormatResult.fromResponse(response);
   }
 }