Remove object-fit polyfill for the old Microsoft Edge (#22693)

* chore: remove object-fit-images and its postcss packages

* chore: update postcss config

* chore: remove object-fit-image from extra_polyfills.js

* chore: remove object-fit property check from load_polyfills.js

app/javascript/mastodon/extra_polyfills.js

@@ -1,6 +1,3 @@
 import 'abortcontroller-polyfill/dist/abortcontroller-polyfill-only';
 import 'intersection-observer';
 import 'requestidlecallback';
-import objectFitImages from 'object-fit-images';
-
-objectFitImages();

app/javascript/mastodon/load_polyfills.js

@@ -23,15 +23,14 @@ function loadPolyfills() {
   );
 
   // Latest version of Firefox and Safari do not have IntersectionObserver.
-  // Edge does not have requestIdleCallback and object-fit CSS property.
+  // Edge does not have requestIdleCallback.
   // This avoids shipping them all the polyfills.
   const needsExtraPolyfills = !(
     window.AbortController &&
     window.IntersectionObserver &&
     window.IntersectionObserverEntry &&
     'isIntersecting' in IntersectionObserverEntry.prototype &&
-    window.requestIdleCallback &&
-    'object-fit' in (new Image()).style
+    window.requestIdleCallback
   );
 
   return Promise.all([