Disable 'prevent this page from creating additional dialog' in Firefox via Javas

-- url of the page with the problem -- : gumi.szigmatrade.hu
-- HikaShop version -- : 3.4
-- Joomla version -- : 3.8.7
-- PHP version -- : 7.2
-- Browser(s) name and version -- : Mozilla Firefox 59.03

Hi,

Unfortunately, there is a new security feature in Firefox which can prevent the page from creating additional dialog. In hikashop almost every validation errror is shown in javascript alert box, and if this feature is enabled, the user cannot see the error.

My question is: How can I disable this feature via Javascipt?

Thanks,
Andras