Permissions-Policy: gamepad - probably experimental

[hamishwillee]

Permissions-Policy: gamepad appears to have been removed in #23470 for the reasons given in #23470 (comment)

The data is definitely wierd and needs to be looked at again.

Specifically,

• That issues says the permission was added in 62, but in my PR of Firefox 91 gamepad permission policy #11770 it went in at 86 behind a preference.
• The comment is that the feature was only supported "on the allow iframe attribute" based on a note that applied only to FF, so would not affect Chrome.
• Chrome indicate it was shipped in 103 but I can't find confirmation https://chromium-review.googlesource.com/c/chromium/src/+/3566388
• Safari asserts to have supported this in tech preview 186 https://webkit.org/blog/14916/release-notes-for-safari-technology-preview-186/ but I can't see it in https://webkit.org/blog/14205/news-from-wwdc23-webkit-features-in-safari-17-beta/
• Not supported in FF, because FF only supports Feature-Policy

@marcoscaceres Do you know if this actually did release in Chrome/Safari, and if so, in what versions

This falls out of the post mdn/content#42544

[github-actions]

Tip: Review these changes grouped by change (recommended for most PRs), or grouped by feature (for large PRs).

[bban160]

FYI @hamishwillee, I am planning to eventually comb through the Permissions Policy compatibility data alongside the docs updates (mdn/content#42534). At a minimum, there are currently many omissions, and I think some features inadvertently got lost in the conversion from Feature Policy to Permissions Policy.

(Sorry for not noticing this PR until you were already on vacation)

[caugner]

I am planning to eventually comb through the Permissions Policy compatibility data alongside the docs updates

FYI #28797 has related Permissions-Policy issues.

[caugner]

According to BCD, Safari does not support the Permission-Policy (see BCD table), but this header may actually be supported since [Safari 18](https://github.com/mdn/browser-compat-data/ blob/67a8c632fbd6e1a4b43ccffbb1575100c87ec46c/browsers/safari.json#L321-L327), see bug 241952 and WebKit/WebKit#25942 in WebKit 619.1.6.

@annevk Can you confirm that your PR added support for the HTTP Permissions-Policy header?

(BCD data also indicates that Safari never supported Feature-Policy, which seems wrong given this WebKit PR, unless the features are in WebKit, but were never enabled in Safari.)