Ensure the API roundtrips for opaque paths

[annevk]

As opaque paths can end in U+0020, those trailing U+0020 code points need to be removed from the path when both query and fragment become null.

Fixes #651.

• At least two implementers are interested (and none opposed):
  • WebKit
  • Gecko
• Tests are written and can be reviewed and commented upon at:
  • URL: hash/search roundtripping with opaque paths web-platform-tests/wpt#37556
• Implementation bugs are filed:
  • Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=1404465
  • Gecko: https://bugzilla.mozilla.org/show_bug.cgi?id=1808215
  • WebKit: https://bugs.webkit.org/show_bug.cgi?id=250004
  • Deno: URL API: ensure it roundtrips for opaque paths denoland/deno#17245
  • Node.js: URL API: ensure it roundtrips for opaque paths nodejs/node#46063
• MDN issue is filed: URL standard update: opaque paths cannot have trailing space mdn/content#23320

(See WHATWG Working Mode: Changes for more details.)

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Preview | Diff

[domenic]

I might be missing something but I think to make web-platform-tests/wpt#37556 pass you need to modify the pathname setter as well. I'm getting data:space vs. data:nospace and sc:space vs. sc:nospace failures when I try to implement this in jsdom/whatwg-url.

[annevk]

Thanks, I first thought I indeed had to update the pathname setter, but then I noticed that it has a no-op path for opaque paths. So I updated the tests some more so we have coverage for non-special URLs with opaque paths and non-opaque paths.