Clean up some warnings (issue 25964)

pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart

Index: pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart
diff --git a/pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart b/pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart
index fa43aa14054eccdc48768e7f56a51804cfab3de6..3505da67c99c4220b16a33fbf5aeb84a4436fd09 100644
--- a/pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart
@@ -12,14 +12,13 @@ import 'package:analysis_server/src/services/completion/completion_performance.d
 import 'package:analysis_server/src/services/completion/dart/completion_manager.dart';
 import 'package:analysis_server/src/services/completion/dart/imported_reference_contributor.dart';
 import 'package:analyzer/dart/element/element.dart';
-import 'package:analyzer/task/dart.dart';
 import 'package:analyzer/src/task/dart.dart';
+import 'package:analyzer/task/dart.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:unittest/unittest.dart';
 
 import '../../../utils.dart';
 import 'completion_contributor_util.dart';
-import 'package:analyzer/src/generated/source.dart';
 
 main() {
   initializeTestEnvironment();