clean UglifyJSPlugin options in production build

Author: KleoPetroff

webpack.production.config.js

@@ -33,15 +33,7 @@ const config = {
       debug: false,
     }),
     new webpack.optimize.UglifyJsPlugin({
-      beautify: false,
-      mangle: {
-        screw_ie8: true,
-        keep_fnames: true,
-      },
-      compress: {
-        screw_ie8: true,
-      },
-      comments: false,
+      beautify: false
     }),
     new webpack.DefinePlugin({ 'process.env': { NODE_ENV: JSON.stringify('production') } }),
     new ExtractTextPlugin({ filename: 'style.css', disable: false, allChunks: true }),