Cookiesync not supported with Internet Explorer 11

[Romain Colombat]

Hi,

First thank you for the lib 🎈!

I've found that cookiesync breaks IE11 and throws Syntax Error.

It breaks at this line exports.cookiesync = (context) => {.

I've tried to polyfill the lib myself but I'm having trouble.

Thank you! It would be very handful to make it work with IE11 as some of our user are still using the browser :/