 this.__dataEnabled = false;
        this.__dataReady = false;
        this.__dataInvalid = false;
        // initialize data with prototype values saved when creating accessors
        this.__data = {};
        this.__dataPending = null;
        this.__dataOld = null;
        if (this.__dataProto) {
          this._initializeProtoProperties(this.__dataProto);
          this.__dataProto = null;
        }
        // Capture instance properties; these will be set into accessors
        // during first flush. 