Stories: Delete { contain: strict } style to fix scrolling in the story archive (#4614)

src/components/ui/Transition.scss

@@ -31,13 +31,7 @@
   &-slideOptimizedBackwards,
   &-slideOptimizedRtl,
   &-slideOptimizedRtlBackwards {
-    contain: strict;
-
-    body.is-safari & {
-      // Create a new composite layer to reduce the page repaint area when switching a tab
-      // Consider experimenting with `contain` when browser support is better
-      transform: translate3d(0, 0, 0);
-    }
+    transform: translate3d(0, 0, 0);
 
     #root & > .Transition_slide {
       position: absolute;