since RC5 the webpack prod build is defect (#2200)

* since RC5 the webpack prod build is defect

Issue #10618 recommends 'mangle: { keep_fnames: true, screw_ie8: true } for the webpack UglifyJs plugin

* remove screw_ie8 option

removed the screw_ie8: true option because it is not necessary

public/docs/_examples/webpack/ts/config/webpack.prod.js

@@ -24,7 +24,11 @@ module.exports = webpackMerge(commonConfig, {
   plugins: [
     new webpack.NoErrorsPlugin(),
     new webpack.optimize.DedupePlugin(),
-    new webpack.optimize.UglifyJsPlugin(),
+    new webpack.optimize.UglifyJsPlugin({ // https://github.com/angular/angular/issues/10618
+      mangle: {
+        keep_fnames: true
+      }
+    }),
     new ExtractTextPlugin('[name].[hash].css'),
     new webpack.DefinePlugin({
       'process.env': {