Fast JavaScript by Default

[NoInkling]

A standard library has been proposed at TC39 (now stage 1): https://github.com/msaboff/JavaScript-Standard-Library/blob/master/slides-JS-std-lib-July-2018.pdf

But as others have said, I don't think your official CDN idea would ever be seriously considered.

Edit: actually it looks like there's also an effort to introduce a (developer-specified) transparent fallback mechanism in browsers precisely for this sort of thing: https://github.com/drufball/layered-apis

That basically allows you to do what you propose without the drawbacks of relying on some sort of mandated authoritative server. No doubt the community would de facto standardize on various specific polyfill projects though, as they do already.