Revert "dart2js_mirrors_test added"

lib/compiler/implementation/lib/mirrors.dart

 // Copyright (c) 2012, 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.
 
-/**
- * The dart:mirrors library provides reflective access for Dart programs.
- *
- * Mirrors are currently only supported by the Dart VM.
- */
 #library("dart:mirrors");
 
 #import("dart:isolate");
 
 #source("../../../mirrors/mirrors.dart");
 
 /**
  * Stub class for the mirror system.
  */
 class _Mirrors {
   static MirrorSystem currentMirrorSystem() {
     throw new UnsupportedOperationException("MirrorSystem not implemented");
   }
 
   static Future<MirrorSystem> mirrorSystemOf(SendPort port) {
     throw new UnsupportedOperationException("MirrorSystem not implemented");
   }
 
   static InstanceMirror reflect(Object reflectee) {
     throw new UnsupportedOperationException("MirrorSystem not implemented");
   }
 }