Upgrade from IDN2003 to UTS #46 Non-transitional

[swankjesse]

There’s a few IDN specs:

• IDNA2003, what OkHttp gets for free from the JVM
• IDNA2008, a spec that never gained widespread adoption
• UTS #46

According to this comment on the URL standard, if we follow non-transitional rules we’ll be in good company with major browsers.

And here’s a handy test suite:
https://wpt.fyi/results/url/toascii.window.html?label=experimental&label=master&aligned

Lets do the following:

• See what APIs Android and OpenJDK offer in this space
• Upgrade to UTS 46 Non-transitional, possibly by writing our own implementation

[swankjesse]

https://github.com/web-platform-tests/wpt/blob/master/url/resources/toascii.json

[yschimke]

relevant to #6910

[swankjesse]

#7789

[swankjesse]

This is implemented! I’ll open a low-priority tracking bug to track some edge cases we could do better on.

[swankjesse]

#7813

[swankjesse]

(I’m not opening tracking bugs for the other suppressed tests; as-is we’re consistent with Chromium on them.)