Deprecate allowpaymentrequest attribute

[marcoscaceres]

closes #925

The following tasks have been completed:

• [X] Confirmed there are no ReSpec errors/warnings.
• [x] Modified Web platform tests
• [ ] Modified MDN Docs (link)
• [ ] Has undergone security/privacy review (link)

Implementation commitment:

• [X] Safari - Never implemented
• [ ] Chrome
• [X] Firefox - never shipped.
• [ ] Edge (public signal)

Optional, impact on Payment Handler spec? None.

Waiting on: https://github.com/whatwg/html/pull/5915 https://github.com/w3c/webappsec-permissions-policy/pull/402

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Preview | Diff

[ianbjacobs]

Looks good (but I am not an implementer).

[marcoscaceres]

(but I am not an implementer).

You are an honorary implementer 😂

[marcoscaceres]

I'm going to migrate the WPTests to use allow="payment", that way we don't lose those existing tests.

[marcoscaceres]

Updated tests at https://github.com/web-platform-tests/wpt/pull/25560

[marcoscaceres]

@stephenmcgruer, seems Chrome night not have gotten updated to match? (the allowpaymentrequest attribute was removed from HTML a few years ago) https://bugs.chromium.org/p/chromium/issues/detail?id=1127988

[stephenmcgruer]

Hey Marcos - yes, we tried to remove allowpaymentrequest previously, but found that usage was too high for a trivial removal. (This is the UseCounter). I admit we then put it aside and failed to come back to it :(, but the next steps for us are to dig into cases where the metric triggers to see if we can identify ways to drive it down. This is tracked in https://crbug.com/1127988