The Feature Policy was renamed Permissions Policy, which also has the implication that:
* the HTTP header was renamed to Permissions-Policy
* all the interfaces and related WebIDL parts got renamed
Additionally, there is a new policy parser, which WebKit doesn't support yet (maybe better as a separate bug, but thought I'd mention it here).
Given that Feature-Policy header has been out for a while, we might need to come up with a transitional strategy, whereby we support both Permissions-Policy and Feature-Policy for a while, but also start notifying sites (via web inspector) that they should move to using the new header.