[flags] make enableScrollEndPolyfill dynamic (facebook#32517)

Will roll this out in www

Author: rickhanlonii

packages/shared/forks/ReactFeatureFlags.www-dynamic.js

@@ -39,6 +39,7 @@ export const enableUseEffectCRUDOverload = __VARIANT__;
 export const enableFastAddPropertiesInDiffing = __VARIANT__;
 export const enableLazyPublicInstanceInFabric = false;
 export const enableViewTransition = __VARIANT__;
+export const enableScrollEndPolyfill = __VARIANT__;
 
 // TODO: These flags are hard-coded to the default values used in open source.
 // Update the tests so that they pass in either mode, then set these

packages/shared/forks/ReactFeatureFlags.www.js

@@ -37,6 +37,7 @@ export const {
   transitionLaneExpirationMs,
   enableFastAddPropertiesInDiffing,
   enableViewTransition,
+  enableScrollEndPolyfill,
 } = dynamicFeatureFlags;
 
 // On WWW, __EXPERIMENTAL__ is used for a new modern build.
@@ -116,7 +117,5 @@ export const enableLazyPublicInstanceInFabric = false;
 
 export const enableSwipeTransition = false;
 
-export const enableScrollEndPolyfill = false;
-
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);