Change line endings from Windows to Unix

tests/compiler/dart2js/mirrors_helper.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.
 
 /**
  * This file is read by 'mirrors_test.dart'.
  */
 
 #library('mirrors_helper');
 
@@ skipping 28 matching lines @@
   var field1;
   int _field2;
   final String field3 = "field3";
 
   int get field2() => _field2;
   void set field2(int value) {
     _field2 = value;
   }
 }