Do not use spread operator in require.js implementation

Reviewed By: jeanlauliac

Differential Revision: D8074917

fbshipit-source-id: e7c4dca7955f7aeda8b59d2039e857f79168410b

packages/metro/src/lib/polyfills/__tests__/require-test.js

@@ -18,17 +18,13 @@ const fs = require('fs');
 
 const {transformSync} = require('@babel/core');
 
-// from: metro/packages/metro-babel-register/babel-register.js
-
-const PLUGINS = [
-  '@babel/plugin-transform-flow-strip-types',
-  '@babel/plugin-proposal-object-rest-spread',
-  '@babel/plugin-proposal-class-properties',
-];
+// Include the external-helpers plugin to be able to detect if they're
+// needed when transforming the requirejs implementation.
+const PLUGINS = ['@babel/plugin-external-helpers'];
 
 function createBabelConfig() {
   return {
-    presets: [],
+    presets: [require.resolve('babel-preset-react-native')],
     plugins: PLUGINS.map(require),
     retainLines: true,
     sourceMaps: 'inline',
@@ -56,6 +52,12 @@ describe('require', () => {
     moduleSystem = {};
   });
 
+  it('does not need any babel helper logic', () => {
+    // Super-simple check to validate that no babel helpers are used.
+    // This check will need to be updated if https://fburl.com/6z0y2kf8 changes.
+    expect(moduleSystemCode.includes('babelHelpers')).toBe(false);
+  });
+
   it('works with plain bundles', () => {
     createModuleSystem(moduleSystem, false);
     expect(moduleSystem.require).not.toBeUndefined();

packages/metro/src/lib/polyfills/require.js

@@ -326,7 +326,7 @@ if (__DEV__) {
         return false;
       }
 
-      parents.push(...inverseDependencies[notAccepted[i]]);
+      parents.push.apply(parents, inverseDependencies[notAccepted[i]]);
     }
 
     return parents.length == 0;