ction() {
      if (this.attrForValue) {
        this._inputElement.addEventListener(this._valueChangedEvent, this._boundValueChanged);
      } else {
        this.addEventListener('input', this._onInput);
      }

      // Only validate when attached if the input already has a value.
      if (this._inputElementValue != '') {
        this._handleValueAndAutoValidate(this._inputElement);
      } else {
        this._handleValue(this._inputElement);
      }
    },

    _onAddonAttached: function(event) {
   