fix: support babel corejs config for modern mode (#6070)

packages/babel-preset-app/src/index.js

@@ -47,7 +47,9 @@ module.exports = (context, options = {}) => {
   const presets = []
   const plugins = []
 
-  const modern = Boolean(options.modern)
+  const modern = options.modern === undefined
+    ? context.env('modern')
+    : Boolean(options.modern)
 
   const {
     polyfills: userPolyfills,

packages/webpack/src/config/modern.js

@@ -12,19 +12,4 @@ export default class WebpackModernConfig extends WebpackClientConfig {
       'process.modern': true
     })
   }
-
-  getBabelOptions () {
-    return {
-      ...this.buildContext.buildOptions.babel,
-      envName: this.name,
-      presets: [
-        [
-          require.resolve('@nuxt/babel-preset-app'),
-          {
-            modern: true
-          }
-        ]
-      ]
-    }
-  }
 }