Revert "Move dart2jslib parts into separate libraries."

tests/compiler/dart2js/simple_inferrer_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:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
 import 'package:compiler/src/types/types.dart' show TypeMask;
 import 'type_mask_test_helper.dart';
 
 import 'compiler_helper.dart';
+import 'parser_helper.dart';
+import 'type_mask_test_helper.dart';
 
 const String TEST = """
 returnNum1(a) {
   if (a) return 1;
   else return 2.5;
 }
 
 returnNum2(a) {
   if (a) return 1.4;
   else return 2;
@@ skipping 848 matching lines @@
     checkReturn('testSpecialization3', typesTask.uint31Type.nullable());
     checkReturn('testReturnNull1', typesTask.nullType);
     checkReturn('testReturnNull2', typesTask.nullType);
     checkReturn('testReturnNull3', typesTask.dynamicType);
     checkReturn('testReturnNull4', typesTask.nullType);
     checkReturn('testReturnNull5', typesTask.nullType);
     checkReturn('testReturnNull6', typesTask.dynamicType);
     checkReturn('testReturnNotEquals', typesTask.boolType);
   }));
 }