fix(formvalidation): improve disabled fields check

Whenever a (required) form field gets disabled by adding the disabled class to the field label (rather than the input itself) after the whole form was initialized, the validation failed.
native required but disabled input fields are ignored by default, so FUI should also support that

Author: lubber-de

src/definitions/behaviors/form.js

@@ -1350,12 +1350,13 @@
                         var
                             identifier    = field.identifier || fieldName,
                             $field        = module.get.field(identifier),
+                            $fieldGroup = $field.closest($group),
                             $dependsField = field.depends
                                 ? module.get.field(field.depends)
                                 : false,
                             fieldValid  = true,
                             fieldErrors = [],
-                            isDisabled = $field.filter(':not(:disabled)').length === 0,
+                            isDisabled = $field.filter(':not(:disabled)').length === 0 || $fieldGroup.hasClass(className.disabled) || $fieldGroup.parent().hasClass(className.disabled),
                             validationMessage = $field[0].validationMessage,
                             noNativeValidation = field.noNativeValidation || settings.noNativeValidation || $field.filter('[formnovalidate],[novalidate]').length > 0 || $module.filter('[novalidate]').length > 0,
                             errorLimit
@@ -1364,15 +1365,15 @@
                             module.debug('Using field name as identifier', identifier);
                             field.identifier = identifier;
                         }
-                        if (validationMessage && !noNativeValidation) {
+                        if (validationMessage && !noNativeValidation && !isDisabled) {
                             module.debug('Field is natively invalid', identifier);
                             fieldErrors.push(validationMessage);
                             fieldValid = false;
                             if (showErrors) {
-                                $field.closest($group).addClass(className.error);
+                                $fieldGroup.addClass(className.error);
                             }
                         } else if (showErrors) {
-                            $field.closest($group).removeClass(className.error);
+                            $fieldGroup.removeClass(className.error);
                         }
                         if (isDisabled) {
                             module.debug('Field is disabled. Skipping', identifier);