refactor: use Object.create polyfill

I need `Object.create` in the pratt parser and IMO it makes sense to use standard Object.create (with a polyfill if needed). This change doesn't increase LOC and the polyfill can be dropped if one doesn't need to support browsers with non-ES5 JS engines.

Polyfill taken from: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/create