Break up another large file

pkg/analyzer/test/source/error_processor_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 analyzer.test.source.error_processor;
 
+import 'package:analyzer/error/error.dart';
 import 'package:analyzer/source/analysis_options_provider.dart';
 import 'package:analyzer/source/error_processor.dart';
 import 'package:analyzer/src/context/context.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart';
-import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/task/options.dart';
 import 'package:plugin/manager.dart';
 import 'package:plugin/plugin.dart';
 import 'package:unittest/unittest.dart';
 import 'package:yaml/src/yaml_node.dart';
 
 import '../generated/test_support.dart';
 
 main() {
   AnalysisError invalid_assignment =
@@ skipping 139 matching lines @@
 void oneTimeSetup() {
   List<Plugin> plugins = <Plugin>[];
   plugins.addAll(AnalysisEngine.instance.requiredPlugins);
   plugins.add(AnalysisEngine.instance.commandLinePlugin);
   plugins.add(AnalysisEngine.instance.optionsPlugin);
   ExtensionManager manager = new ExtensionManager();
   manager.processPlugins(plugins);
 }
 
 class TestContext extends AnalysisContextImpl {}