feat: update uglifyjs-webpack-plugin to 2.2.0

closes #454

Author: jlengrand

config/webpack.config.prod.js

@@ -61,13 +61,13 @@ module.exports = {
     minimizer: [
       new UglifyJsPlugin({
         uglifyOptions: {
+          warnings: false,
           // ES5 is required in the minified code if you want compatibility with IE11,
           // otherwise you can bump it up to ES8
           ecma: 5,
           // Compression settings mostly based on <https://guide.elm-lang.org/optimization/asset_size.html>
           compress: {
             passes: 2,
-            warnings: false,
             // Disabled because of an issue with Uglify breaking seemingly valid code:
             // https://github.com/facebook/create-react-app/issues/2376
             // Pending further investigation:
@@ -96,9 +96,6 @@ module.exports = {
               'F9',
             ],
           },
-          mangle: {
-            safari10: true,
-          },
           output: {
             comments: false,
             // Turned on because emoji and regex is not minified properly using default

package.json

@@ -59,7 +59,7 @@
     "string-replace-loader": "2.3.0",
     "strip-ansi": "6.0.0",
     "style-loader": "1.2.1",
-    "uglifyjs-webpack-plugin": "1.3.0",
+    "uglifyjs-webpack-plugin": "2.2.0",
     "url-loader": "4.1.0",
     "webpack": "4.44.2",
     "webpack-dev-server": "3.11.0",