Auto merge of #26407 - mrobinson:animation-restyle-model, r=jdm

Have animations more closely match the HTML spec

These two commits do two major things:

**Have animations ticks trigger a restyle**: This corrects synchronization issues with animations,
where the values used in layout are out of sync with what is returned by `getComputedStyle`.

**Tick the animation timer in script according to spec**: This greatly reduces the flakiness of
animation and transitions tests.

Fixes #13865.

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---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #13865

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- [x] There are tests for these changes OR
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tests/wpt/mozilla/meta/MANIFEST.json

@@ -12871,7 +12871,7 @@
       ]
      ],
      "transition-raf.html": [
-      "6159bb9ab333544b4485d11025889ee94186c7eb",
+      "c38404503408e04b3c75b42df18ec3a7ec0819f5",
       [
        null,
        {}