Bug 1602318 - Allow less a smaller number of pref checks. r=mconley

Differential Revision: https://phabricator.services.mozilla.com/D70625

browser/base/content/test/performance/browser_preferences_usage.js

@@ -198,7 +198,7 @@ add_task(async function navigate_around() {
       // This is accessed in debug only.
     },
     "toolkit.cosmeticAnimations.enabled": {
-      min: 45,
+      min: 30,
       max: 55,
     },
   };