Add equivalence testing on JS nodes to support different label names

tests/compiler/dart2js/kernel/compile_from_dill_fast_startup_test.dart

 // Copyright (c) 2017, 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.
 
 // Test compilation equivalence between source and .dill based
 // compilation using the fast_startup emitter.
 library dart2js.kernel.compile_from_dill_fast_startup_test;
 
-import 'dart:async';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/commandline_options.dart';
-import '../serialization/helper.dart';
 
 import 'compile_from_dill_test_helper.dart';
 
 main(List<String> args) {
   asyncTest(() async {
-    await mainInternal(args);
+    await runTests(args, options: [Flags.fastStartup]);
   });
 }
-
-Future<ResultKind> mainInternal(List<String> args,
-    {bool skipWarnings: false, bool skipErrors: false}) async {
-  Arguments arguments = new Arguments.from(args);
-  Uri entryPoint;
-  Map<String, String> memorySourceFiles;
-  if (arguments.uri != null) {
-    entryPoint = arguments.uri;
-    memorySourceFiles = const <String, String>{};
-  } else {
-    entryPoint = Uri.parse('memory:main.dart');
-    memorySourceFiles = SOURCE;
-  }
-
-  return runTest(entryPoint, memorySourceFiles,
-      verbose: arguments.verbose,
-      skipWarnings: skipWarnings,
-      skipErrors: skipErrors,
-      options: [Flags.fastStartup]);
-}