lts = this._defaults || new WeakMap();
        var nodes = this._getSubmittableElements();
        for (var i = 0; i < nodes.length; i++) {
          var node = nodes[i];
          if (!this._defaults.has(node)) {
            this._defaults.set(node, {
              checked: node.checked,
              value: node.value,
            });
          }
        }
      },

      /**
       * Validates all the required elements (custom and native) in the form.
       * @return {boolean} True if all the elements a