LibWeb/CSS: Mark transform property as resolving percentages as lengths

Author: https://github.com/AtkinsSJ
Commit: https://github.com/LadybirdBrowser/ladybird/commit/6f60c258cec
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3198

Libraries/LibWeb/CSS/Properties.json

@@ -2723,7 +2723,8 @@
     "inherited": false,
     "initial": "none",
     "affects-layout": false,
-    "affects-stacking-context": true
+    "affects-stacking-context": true,
+    "percentages-resolve-to": "length"
   },
   "transform-box": {
     "animation-type": "discrete",