fix #43, remove => workaround

bin/devrun.dart

 #!/usr/bin/env dart
 // Copyright (c) 2015, 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.
 
 /// Runs io.js with dev_compiler's generated code.
 library dev_compiler.bin.devrun;
 
 import 'dart:io';
 
@@ skipping 10 matching lines @@
 
 void _showUsageAndExit() {
   print('usage: ${_appName} [<options>] <file.dart>\n');
   print('<file.dart> is a single Dart file to run.\n');
   print('<options> include:\n');
   print(argParser.usage);
   exit(1);
 }
 
 main(List<String> args) async {
-  args = []
-    ..add('--arrow-fn-bind-this')
-    ..addAll(args);
-
   CompilerOptions options;
 
   try {
     options = validateOptions(args, forceOutDir: true);
   } on FormatException catch (e) {
     print('${e.message}\n');
     _showUsageAndExit();
   }
 
   if (options == null || options.help) _showUsageAndExit();
@@ skipping 40 matching lines @@
 
   stderr.writeln(
       'Wrote $htmlOutput. It can be opened in Chrome Dev with the following flags:\n'
       '--js-flags="--harmony-arrow-functions '
       '--harmony-classes '
       '--harmony-computed-property-names '
       '--harmony_destructuring '
       '--harmony-spreadcalls"'
       '\n');
 }