Move dromaeo to third_party

samples/third_party/dromaeo/common/JSON.dart

 // Copyright (c) 2011, 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.
 
 // Pure Dart implementation of JSON protocol.
 
 /**
  * Utility class to parse JSON and serialize objects to JSON.
  */
 class JSON {
@@ skipping 564 matching lines @@
           }
         });
         _sb.add('}');
         return;
 
       default:
         throw const JsonUnsupportedObjectType();
     }
   }
 }