`_removedFields` should private and not enumerable, like what the `Resource` class does with its internal `DataStore` instance.  This ensures it is not rendered when JSONified.

Example:

    var _removedFields = null; //private var, not enumerable
    Object.defineProperty(this, 'removedFields', {
      get: function getRemovedFields() {
        return _removedFields;
      },
      set: function setRemovedFields(removedFields) {
        _removedFields = dataStore;
      }
    });
    this._removedFields = [];

Let me know if I'm missing something.