Bug 1737211 - Fix translate-interpolation.html. r=layout-reviewers,boris

Stripping the percentageness from calc() interpolation is not correct,
see w3c/csswg-drafts#3482.

Differential Revision: https://phabricator.services.mozilla.com/D130459

Author: emilio

testing/web-platform/meta/css/css-transforms/animation/translate-interpolation.html.ini

@@ -122,7 +122,7 @@
         to: '240% 160%',
       }, [
         {at: -1, expect: 'calc(960px - 240%) calc(800px - 160%) 640px'},
-        {at: 0, expect: '480px 400px 320px'},
+        {at: 0, expect: 'calc(0% + 480px) calc(0% + 400px) 320px'},
         {at: 0.125, expect: 'calc(420px + 30%) calc(350px + 20%) 280px'},
         {at: 0.875, expect: 'calc(210% + 60px) calc(140% + 50px) 40px'},
         {at: 1, expect: '240% 160%'},