Break up another large file

pkg/analyzer/test/generated/engine_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.engine_test;
 
 import 'dart:async';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/error/error.dart';
 import 'package:analyzer/plugin/resolver_provider.dart';
 import 'package:analyzer/src/cancelable_future.dart';
 import 'package:analyzer/src/context/builder.dart' show EmbedderYamlLocator;
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/context/context.dart';
 import 'package:analyzer/src/context/source.dart';
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/engine.dart';
-import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:analyzer/src/string_source.dart';
 import 'package:analyzer/task/model.dart';
 import 'package:html/dom.dart' show Document;
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:typed_mock/typed_mock.dart';
 import 'package:unittest/unittest.dart';
 
 import '../utils.dart';
@@ skipping 675 matching lines @@
   @override
   void test_flushAstStructures(Source source) {
     fail("Unexpected invocation of test_flushAstStructures");
   }
 
   @override
   void visitContentCache(ContentCacheVisitor visitor) {
     fail("Unexpected invocation of visitContentCache");
   }
 }