Move dart2jslib parts into separate libraries.

tests/compiler/dart2js/simple_inferrer_relations_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 '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
 // to if ($.$eq(x, y) == true)
 // This is an optimization based on seeing that all the relational operators,
 // ==, <, >, <=, >= only have implementations that return bool.
 
 const String TEST = """
 int inscrutable(int x) => x == 0 ? 0 : x | inscrutable(x & (x - 1));
 
@@ skipping 29 matching lines @@
 """;
 
 void main() {
   asyncTest(() => compileAll(TEST).then((generated) {
     if (generated.contains(r'=== true')) {
       print(generated);
       Expect.fail("missing elision of '=== true'");
     }
   }));
 }