URL IDNA interop

[annevk]

Description
IDNA allows for us non-ASCII code points in domain names.

Specification
https://url.spec.whatwg.org/#idna

Tests
https://wpt.fyi/results/url/toascii.window.html (to be modified by web-platform-tests/wpt#31596 to show the issue better)

Rationale
Firefox and Safari follow the URL Standard and use Transitional_Processing set to false, but Chrome does not. Firefox has some unrelated failures on this particular test, I'm not sure whether those should be in scope or not.

[foolip]

How would this affect developers? Is this something that currently leads to site compat issues, or do web developers have to avoid IDNA domain names because of issues like this?

[annevk]

Yeah, for instance German speakers cannot have domains with ß in them as they do not work in Chrome (becomes ss rather than xn--zca). And on the other side, URLs such as https://www.👨‍🦰.tk/ only work in Chrome (but shouldn't).

[jgraham]

I'm going to move this to be a candiate for #9 rather than a standalone proposal.

[foolip]

@annevk is https://bugs.chromium.org/p/chromium/issues/detail?id=694157 the right Chromium bug for this? I see Transitional_Processing vs. Nontransitional_Processing but maybe there was a rename at some point?

[foolip]

Yep, it was renamed in whatwg/url#404.

[dholbert]

Firefox has some unrelated failures on this particular test, I'm not sure whether those should be in scope or not.

Following up on these: I filed https://bugzilla.mozilla.org/show_bug.cgi?id=1788115 on these failures, and that bug's just been fixed, making tomorrow's Firefox Nightly fully pass this test now. Hooray!

[gsnedders]

#145 covers a superset of this in Interop 2023. (And the above linked tests are still failing in Chrome.)