Update the polyfill to the latest API

[jridgewell]

No description provided.

[erights]

Hi @jridgewell @legendecas @littledan ,

How faithful is this polyfill to the proposal? Where does it differ? Does it or could it use the Node async_hooks API to more faithfully emulate the full proposal?

Attn @gibson042

[jridgewell]

The implementation details in src/ aren't from the proposal, it's just a strategy that allows mutating the storage Map directly, and cloning as necessary when we "revert" back to the previous state. So instead of always cloning on enter, it mutates on enter (if the map isn't already frozen) and mutates to exit (if the still isn't frozen).

This also doesn't patch any of the JS standard library, doesn't implement user async/generator functions, etc. Node's async_hooks doesn't capture the generator's init-time context, so we'd have to wrap or transpile generators to get the correct behavior.

@andreubotella has a fork of engine262 that might be up to date (?) if you're looking for appropriate spec implementations. If you're just looking for high level details, the proposal is still basically the same as what we discussed last year, just with an updated public API. The internal implementation is still a Map or LinkedList depending on how the engines want to optimize.