Update to @rollup/plugin-babel (#30742)

build/babel-helpers.js

@@ -1,14 +0,0 @@
-'use strict'
-
-// These are the babel helpers we whitelist
-const helpers = [
-  'createClass',
-  'createSuper',
-  'defineProperties',
-  'defineProperty',
-  'getPrototypeOf',
-  'inheritsLoose',
-  'objectSpread2'
-]
-
-module.exports = helpers

build/build-plugins.js

@@ -11,16 +11,15 @@
 
 const path = require('path')
 const rollup = require('rollup')
-const babel = require('rollup-plugin-babel')
+const { babel } = require('@rollup/plugin-babel')
 const banner = require('./banner.js')
-const babelHelpers = require('./babel-helpers.js')
 
 const plugins = [
   babel({
     // Only transpile our source code
     exclude: 'node_modules/**',
-    // Include only required helpers
-    externalHelpersWhitelist: babelHelpers
+    // Inline the required helpers in each file
+    babelHelpers: 'inline'
   })
 ]
 const bsPlugins = {

build/rollup.config.js

@@ -1,10 +1,9 @@
 'use strict'
 
 const path = require('path')
-const babel = require('rollup-plugin-babel')
+const { babel } = require('@rollup/plugin-babel')
 const resolve = require('@rollup/plugin-node-resolve')
 const banner = require('./banner.js')
-const babelHelpers = require('./babel-helpers.js')
 
 const BUNDLE = process.env.BUNDLE === 'true'
 const ESM = process.env.ESM === 'true'
@@ -15,8 +14,8 @@ const plugins = [
   babel({
   // Only transpile our source code
     exclude: 'node_modules/**',
-    // Include only required helpers
-    externalHelpersWhitelist: babelHelpers
+    // Include the helpers in the bundle, at most one copy of each
+    babelHelpers: 'bundled'
   })
 ]
 const globals = {