Revert "Move dart2jslib parts into separate libraries."

tests/compiler/dart2js/simple_inferrer_postfix_prefix_test.dart

 // Copyright (c) 2013, 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.
 
-import 'package:async_helper/async_helper.dart';
 import 'package:expect/expect.dart';
-
+import "package:async_helper/async_helper.dart";
 import 'compiler_helper.dart';
+import 'parser_helper.dart';
 import 'type_mask_test_helper.dart';
 
 const String TEST = """
 
 class A {
   get foo => 'string';
   set foo(value) {}
   operator[](index) => 'string';
   operator[]=(index, value) {}
 
@@ skipping 72 matching lines @@
     checkReturnInClass('A', 'returnEmpty3', const TypeMask.nonNullEmpty());
 
     checkReturnInClass('B', 'returnString1', typesTask.stringType);
     checkReturnInClass('B', 'returnString2', typesTask.stringType);
     checkReturnInClass('B', 'returnDynamic1', const TypeMask.nonNullEmpty());
     checkReturnInClass('B', 'returnDynamic2', const TypeMask.nonNullEmpty());
     checkReturnInClass('B', 'returnDynamic3', const TypeMask.nonNullEmpty());
     checkReturnInClass('B', 'returnDynamic4', const TypeMask.nonNullEmpty());
   }));
 }