Update webpack.config.dev.js

You do not have use alias for thing you do. modulesDirectories should work.

facebook#1136
facebook#276
facebook#253

The change breaks tooling and you should not use it until issues are resolved with it.

Author: marcelmokos

packages/react-scripts/config/webpack.config.dev.js

@@ -87,8 +87,11 @@ module.exports = {
     // some tools, although we do not recommend using it, see:
     // https://github.com/facebookincubator/create-react-app/issues/290
     extensions: ['.js', '.json', '.jsx', ''],
+    modulesDirectories: [
+      'src',
+      'node_modules'
+    ],
     alias: {
-      '@src': paths.appSrc,
       // Support React Native Web
       // https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
       'react-native': 'react-native-web'