enable code completion integration test stub

pkg/analysis_server/test/operation/test_all.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.operation.all;
+
 import 'package:unittest/unittest.dart';
 
 import 'operation_queue_test.dart' as operation_queue_test;
 import 'operation_test.dart' as operation_test;
 
 /**
  * Utility for manually running all tests.
  */
 main() {
   groupSep = ' | ';
   group('operation', () {
     operation_queue_test.main();
     operation_test.main();
   });
 }