Yeah, my first thought when seeing that it uses Symbol and Proxy was that Proxy can't be polyfilled. But it looks like there's partial polyfills for it: https:/

Yeah, my first thought when seeing that it uses Symbol and Proxy was that Proxy can't be polyfilled. But it looks like there's partial polyfills for it: https://www.google.com/url?sa=t&source=web&rct=j&url=https://github.com/GoogleChrome/proxy-polyfill&ved=2ahUKEwjVptCr5ZfaAhURjlkKHe1MB9sQFjAAegQIBxAB&usg=AOvVaw0nUHNMpcd0EoEqYO_Csr4A https://www.google.com/url?sa=t&source=web&rct=j&url=https:/...