Move dart2jslib parts into separate libraries.

tests/compiler/dart2js/simple_inferrer_relations_test.dart

Index: tests/compiler/dart2js/simple_inferrer_relations_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_relations_test.dart b/tests/compiler/dart2js/simple_inferrer_relations_test.dart
index de080f4d7fddb0074d3b2a048d5d12c9d3161b6c..a076955af820a68ebd0828112cfdbe831c6bde78 100644
--- a/tests/compiler/dart2js/simple_inferrer_relations_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_relations_test.dart
@@ -2,12 +2,10 @@
 // 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 'package:compiler/src/types/types.dart' show TypeMask;
 
 import 'compiler_helper.dart';
-import 'parser_helper.dart';
 
 // Test that if (x == y) where we know nothing about x and y will get optimized
 // to if ($.$eq(x, y)) and not