 = this.closingReason || {};
      this.closingReason.canceled = this.canceled;
    },

    _withBackdropChanged: function() {
      // If tabindex is already set, no need to override it.
      if (this.withBackdrop && !this.hasAttribute('tabindex')) {
        this.setAttribute('tabindex', '-1');
        this.__shouldRemoveTabIndex = true;
      } else if (this.__shouldRemoveTabIndex) {
        this.removeAttribute('tabindex');
        this.__shouldRemoveTabIndex = false;
      }
      if (this.opened) {
  