[Meta] Should ECMA262 pull requests be listed here or just as issues on the main repository?

Because not everything put through TC39 goes through the proposal process there should probably be some tracking of the so called "Needs consensus PRs". It's probably not worth tracking the many ones that are pending or didn't achieve consensus in Babel but any that have achieved consensus should almost certainly be tracked in Babel.

Here's a short list of some of the recent consensus-achieved PRs and their status in Babel:

PR | Babel Status | Notes
----|--------|------
[#785](https://github.com/tc39/ecma262/pull/785) | Fixed (in polyfill)
[#833](https://github.com/tc39/ecma262/pull/833) | Not fixed | Fixable if Proxy itself is already available
[#984](https://github.com/tc39/ecma262/pull/984) | Not fixed | Still a runtime early but should be early error in Babylon
[#988](https://github.com/tc39/ecma262/pull/988) / [#1021](https://github.com/tc39/ecma262/pull/1021) | Not fixed
[#890](https://github.com/tc39/ecma262/pull/890) | Not fixed
[#1005](https://github.com/tc39/ecma262/pull/1005) | Fixed | Already a babel transform

Review the listed ECMA262 pull requests and their Babel statuses, then compare them with how this repository currently tracks proposals. Decide whether consensus-achieved PRs belong here or in Babel's main repository; done means an agreed tracking policy and an updated list or location.

Written by the indexing model from the issue text.