Break up another large file

pkg/analyzer/test/generated/static_warning_code_test.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 analyzer.test.generated.static_warning_code_test;
 
+import 'package:analyzer/error/error.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/generated/source_io.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:unittest/unittest.dart';
 
 import '../utils.dart';
 import 'resolver_test_case.dart';
 
 main() {
   initializeTestEnvironment();
   defineReflectiveTests(StaticWarningCodeTest);
@@ skipping 3661 matching lines @@
 
   void test_voidReturnForGetter() {
     Source source = addSource(r'''
 class S {
   void get value {}
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [StaticWarningCode.VOID_RETURN_FOR_GETTER]);
   }
 }