Add polifils about saleor-storefront

[maarcingebala]

@mociepka Is this issue still valid? If yes, then could you provide some more description so we can work on that?

[mociepka]

This issue is about adding babel polifils:
https://babeljs.io/docs/en/babel-polyfill#docsNav

[mahdikhosravi]

As of Babel 7.4.0, this package has been deprecated in favor of directly including core-js/stable (to polyfill ECMAScript features) and regenerator-runtime/runtime (needed to use transpiled generator functions)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[mociepka]

@bogdal did we tested storefront on browsers different that newest Chrome? Maybe we don't even need this polyfils?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.