Vue 项目在 Safari 中访问为空白页Safari 浏览器不支持ES6语法导致，修改 webpack.prod.c

Safari 浏览器不支持ES6语法导致，修改 webpack.prod.conf.js，添加 mangle 设置

...
plugins: [
    new webpack.DefinePlugin({
      'process.env': env
    }),
    new UglifyJsPlugin({
      uglifyOptions: {
        compress: {
          warnings: false,
          drop_debugger: true,
          drop_console: true
        },
        mangle: {
          safari10: true
        }
      }
...