Bump uglifyjs-webpack-plugin from 1.1.8 to 1.2.0 in /www (#842)

* Bump uglifyjs-webpack-plugin from 1.1.8 to 1.2.0 in /www

Bumps [uglifyjs-webpack-plugin](https://github.com/webpack-contrib/uglifyjs-webpack-plugin) from 1.1.8 to 1.2.0.
- [Release notes](https://github.com/webpack-contrib/uglifyjs-webpack-plugin/releases/tag/v1.2.0)
- [Changelog](https://github.com/webpack-contrib/uglifyjs-webpack-plugin/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/uglifyjs-webpack-plugin@v1.1.8...v1.2.0)

* Use UglifyJS2 safari10 option

www/package.json

@@ -89,7 +89,7 @@
     "stylelint-config-standard": "^18.0.0",
     "stylelint-order": "^0.8.0",
     "stylelint-webpack-plugin": "^0.10.2",
-    "uglifyjs-webpack-plugin": "^1.1.8",
+    "uglifyjs-webpack-plugin": "^1.2.0",
     "url-loader": "^0.6.2",
     "webpack": "^3.11.0",
     "webpack-dev-server": "^2.11.1",

www/webpack/webpack.parts.js

@@ -176,10 +176,6 @@ exports.minifyJavascript = () =>
         sourceMap: true,
         // See: https://github.com/mishoo/UglifyJS2/tree/harmony
         uglifyOptions: {
-          mangle: {
-            // Required to avoid Safari 10 bug https://github.com/mishoo/UglifyJS2/issues/1753
-            safari10: true,
-          },
           // Don't beautify output (enable for neater output).
           beautify: false,
           // Eliminate comments.
@@ -189,6 +185,8 @@ exports.minifyJavascript = () =>
             // Two passes yield the most optimal results
             passes: 2,
           },
+          // Required to avoid Safari 10/11 bugs
+          safari10: true,
         },
       }),
     ],

www/yarn.lock

@@ -8683,9 +8683,9 @@ uglifyjs-webpack-plugin@^0.4.6:
     uglify-js "^2.8.29"
     webpack-sources "^1.0.1"
 
-uglifyjs-webpack-plugin@^1.1.8:
-  version "1.1.8"
-  resolved "https://registry.yarnpkg.com/uglifyjs-webpack-plugin/-/uglifyjs-webpack-plugin-1.1.8.tgz#1302fb9471a7daf3d0a5174da6d65f0f415e75ad"
+uglifyjs-webpack-plugin@^1.2.0:
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/uglifyjs-webpack-plugin/-/uglifyjs-webpack-plugin-1.2.0.tgz#f706fa4c655000a086b4a97c7d835ed0f6e9b0ef"
   dependencies:
     cacache "^10.0.1"
     find-cache-dir "^1.0.0"