Document test updates associated with amendments

[dontcallmedom]

This is a first pass at associating amendments to the relevant test cases and updates made to WPT as part of the amendment documenting process.

I have not documented associated test updates for the following PRs: #2758 #2759 #2794 #2797 #2801 #2847 #2853 #2861 - most likely because no updates were brought, but it could be that I missed them too.

It would be useful if someone could review that the annotations made in amendments.json are correct. Namely that:

• [x] the changes in the following PRs aren't usefully testable (either because they refer to implementation dependent decisions, or because they don't impact what's exposed to JS): #2679 #2686 #2700 #2704 #2753 #2767 #2808 #2814 #2834 #2841 #2885
• [x] the changes in the following PRs were already tested (in general, because the change in the spec is made to match implementations): #2680 #2742 #2829 #2875 #2876
• [x] the association between the other PRs and their WPT PRs is correct and covers sufficiently the said change:
  • [x] #2687 → web-platform-tests/wpt#43171
  • [x] #2689 → web-platform-tests/wpt#43167
  • [x] #2691 → web-platform-tests/wpt#43166
  • [x] #2708 -> web-platform-tests/wpt#21025
  • [x] #2744 #2748 #2832 → web-platform-tests/wpt#35703 web-platform-tests/wpt#43172
  • [x] #2754 → web-platform-tests/wpt#34912
  • [x] #2763 → web-platform-tests/wpt#36157
  • [x] #2772 → web-platform-tests/wpt#37477
  • [x] #2773 → web-platform-tests/wpt#36572
  • [x] #2774 → web-platform-tests/wpt#37477
  • [x] #2775 → web-platform-tests/wpt#37477
  • [x] #2785 → web-platform-tests/wpt#43173
  • [x] #2797 → web-platform-tests/wpt#37477
  • [x] #2799 → web-platform-tests/wpt#37477
  • [x] #2800 → web-platform-tests/wpt#37477
  • [x] #2813 → web-platform-tests/wpt#36155 web-platform-tests/wpt#37477
  • [x] #2813 → web-platform-tests/wpt#37477
  • [x] #2902 → https://phabricator.services.mozilla.com/D190744
  • [x] #2909 → web-platform-tests/wpt#41663
  • [x] #2913 → web-platform-tests/wpt#43601

Merging this PR will also require that any new amendment documents its test status (either as "already-tested", "not-testable", or as an array of pointers to WPT pull requests).

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[henbos]

There are WebIDL validation steps failing, can you take a look @dontcallmedom ?

[dontcallmedom]

I did - I think they're bogus (since this PR doesn't touch the document at all), but in any case, I can spend more time on them once there is approval at least with the principles and the data :)

[henbos]

Ack, @jan-ivar to take a closer look, but free free to merge if he is happy about doing so

[henbos]

PTAL @jan-ivar :)

[youennf]

If the tool requires to put a test status in the amendment, we might need a 'to-be-added-shortly' state, as implementation might not be yet available.