Allow @tc39-staging to modify features.txt

[syg]

This came up while working on the V8 test262 2-way sync bot for staging/. It is likely that tests added to staging/ will be for a new feature that requires a new entry in features.txt, so the staging group should have write access to that file.

cc @rmahdav

[ljharb]

makes sense to me

[syg]

An alternative here is to just... not lint it. I guess the downside is typos are more likely? Does anyone recall the rationale for why there's an list of allowed features in the first place?

[ljharb]

I would assume it's because it was a common problem that people would typo feature names, and, that having a list ensures that there's a central place for discovery.

[Ms2ger]

This is fine by me, but maybe give it a little longer before merging

[ptomato]

This has the unexpected (to me, at least) side effect that the tc39-staging team will get pinged for a review every time someone modifies features.txt. Seems harmless, but just mentioning it in case anyone wonders why it's happening.

[syg]

This has the unexpected (to me, at least) side effect that the tc39-staging team will get pinged for a review every time someone modifies features.txt. Seems harmless, but just mentioning it in case anyone wonders why it's happening.

Seems like a positive side effect to me tbh. I appreciate being pinged on when new feature tests land.