Break up another large file

pkg/analysis_server/test/protocol_server_test.dart

Index: pkg/analysis_server/test/protocol_server_test.dart
diff --git a/pkg/analysis_server/test/protocol_server_test.dart b/pkg/analysis_server/test/protocol_server_test.dart
index 4a667bbca806610f971e3f0e5c016766b06cfc6e..bcbe18ee660bbab07106ba5b6c3bd71c472dbe14 100644
--- a/pkg/analysis_server/test/protocol_server_test.dart
+++ b/pkg/analysis_server/test/protocol_server_test.dart
@@ -12,7 +12,8 @@ import 'package:analysis_server/src/services/search/search_engine.dart';
 import 'package:analyzer/dart/ast/ast.dart' as engine;
 import 'package:analyzer/dart/element/element.dart' as engine;
 import 'package:analyzer/dart/element/type.dart' as engine;
-import 'package:analyzer/src/generated/error.dart' as engine;
+import 'package:analyzer/error/error.dart' as engine;
+import 'package:analyzer/src/error/codes.dart' as engine;
 import 'package:analyzer/src/generated/source.dart' as engine;
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:typed_mock/typed_mock.dart';