Add missing trailing comma

Summary: Adds missing comma, following up on https://github.com/facebook/react-native/pull/20178. Thanks to LinusU for pointing out the error.

Reviewed By: TheSavior

Differential Revision: D9242887

fbshipit-source-id: 4b547396722d0e37dc5c8eb3439b9a441c3c0ac2

jest/preprocessor.js

@@ -39,15 +39,12 @@ module.exports = {
   process(src /*: string */, file /*: string */) {
     if (nodeFiles.test(file)) {
       // node specific transforms only
-      return babelTransformSync(
-        src,
-        {
-          filename: file,
-          sourceType: 'script',
-          ...nodeOptions,
-          ast: false
-        },
-      ).code;
+      return babelTransformSync(src, {
+        filename: file,
+        sourceType: 'script',
+        ...nodeOptions,
+        ast: false,
+      }).code;
     }
 
     const {ast} = transformer.transform({