[];
      // Holds the initial values of the custom elements registered with this form.
      this._customElementsInitialValues = [];
    },

    /**
     * Submits the form.
     */
    submit: function() {
      if (!this.noValidate && !this.validate()) {
        // In order to trigger the native browser invalid-form UI, we need
        // to do perform a fake form submit.
        if (Polymer.clientSupportsFormValidationUI && !this.disableNativeValidationUi) {
          this._doFakeSubmitForValidation();
