fix(@angular/cli): ensure purify is before uglify

Author: filipesilva

packages/@angular/cli/models/webpack-configs/production.ts

@@ -127,6 +127,8 @@ export function getProdConfig(wco: WebpackConfigOptions) {
       }),
       new webpack.HashedModuleIdsPlugin(),
       new webpack.optimize.ModuleConcatenationPlugin(),
+      ...extraPlugins,
+      // Uglify should be the last plugin as PurifyPlugin needs to be before it.
       new UglifyJSPlugin({
         sourceMap: buildOptions.sourcemaps,
         uglifyOptions: {
@@ -141,7 +143,6 @@ export function getProdConfig(wco: WebpackConfigOptions) {
           },
         }
       }),
-      ...extraPlugins
     ]
   };
 }