restore arrow function bind this workaround

tool/input_sdk/private/js_mirrors.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.
 
 library dart._js_mirrors;
 
 import 'dart:collection';
 import 'dart:mirrors';
 import 'dart:_foreign_helper' show JS;
 import 'dart:_internal' as _internal;
 
-// TODO(vsm): This a workaround for:
-// https://github.com/dart-lang/dev_compiler/issues/219
-import 'dart:js';
-
 String getName(Symbol symbol) =>
     _internal.Symbol.getName(symbol as _internal.Symbol);
 
 Symbol getSymbol(name, library) =>
     throw new UnimplementedError("MirrorSystem.getSymbol unimplemented");
 
 final currentJsMirrorSystem = throw new UnimplementedError(
     "MirrorSystem.currentJsMirrorSystem unimplemented");
 
 InstanceMirror reflect(reflectee) => new JsInstanceMirror._(reflectee);
@@ skipping 141 matching lines @@
     for (var i = 0; i < opts.length; ++i) {
       var type = opts[i];
       // TODO(vsm): Recover the param name.
       var param = new JsParameterMirror._('', type);
       params[i + args.length] = param;
     }
 
     return params;
   }
 }