feat(build): Use babel 7

Author: jourdain

.babelrc

@@ -0,0 +1,4 @@
+module.exports = {
+  presets: ['@babel/preset-env'],
+  plugins: ['@babel/plugin-syntax-dynamic-import'],
+};

babel.config.js

@@ -1,4 +1,4 @@
-const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
+const TerserPlugin = require('terser-webpack-plugin');
 const HtmlWebpackPlugin = require('html-webpack-plugin');
 const merge = require('webpack-merge');
 
@@ -10,16 +10,12 @@ const PORT = process.env.PORT && Number(process.env.PORT);
 module.exports = merge(baseConfig, {
   mode: 'production',
   optimization: {
+    occurrenceOrder: true,
     minimizer: [
-      new UglifyJsPlugin({
+      new TerserPlugin({
         cache: true,
         parallel: true,
-        uglifyOptions: {
-          compress: {
-            // uglifyjs bug: https://github.com/webpack/webpack/issues/6567
-            inline: false,
-          },
-        },
+        sourceMap: true,
       }),
     ],
   },