Sginal should be polyfill to global

[yinxulai]

This package is named a "*-polyfill", but its behavior is quite different from other typical polyfills. Most polyfills register the target to the global or tagetprototype, such as:

promise-polyfill
object.assign
Array.prototype.map

We should consider whether this approach is appropriate, and whether the current implementation makes it difficult for multiple packages to share the same polyfill.

[ljharb]

I maintain the second two, and no, they do not automatically modify the global - quite intentionally, as that behavior is dangerous.

Providing an opt-in mechanism to do so would be great, though, although i hope it would wait until the proposal is at stage 3.

[yinxulai]

Providing an opt-in mechanism to do so would be grea

This is great, this allows me to call Signal in a more good way, what can I do to help we achieve this?