RN: Disable Babel Plugin for Arrow Functions for Hermes (#44534)

Summary:
Pull Request resolved: #44534

Reapplies {D50818568} (reverted by D50885400).

Changelog:
[General][Changed] - Disable Babel plugin for arrow functions for Hermes

Reviewed By: robhogan

Differential Revision: D57242622

fbshipit-source-id: 63ec2aeb7562dbb1a049dedd6a35b10aa822193c

packages/react-native-babel-preset/src/configs/main.js

@@ -84,9 +84,9 @@ const getPreset = (src, options) => {
     extraPlugins.push([require('@babel/plugin-transform-classes')]);
   }
 
-  // TODO(gaearon): put this back into '=>' indexOf bailout
-  // and patch react-refresh to not depend on this transform.
-  extraPlugins.push([require('@babel/plugin-transform-arrow-functions')]);
+  if (!isHermes && (isNull || src.includes('=>'))) {
+    extraPlugins.push([require('@babel/plugin-transform-arrow-functions')]);
+  }
 
   if (!isHermes) {
     extraPlugins.push([require('@babel/plugin-transform-computed-properties')]);