message: fix uglify upgrade
diff: @@ -46,9 +46,7 @@ function buildEntry (config) {
  const code = bundle.generate(config).code
  if (isProd) {
  var minified = (config.banner ? config.banner + '\n' : '') + uglify.minify(code, {
  - fromString: true,
  output: {
  - screw_ie8: true,
  ascii_only: true
  },
  compress: {
  