webpack 配置里這兩個(gè)是干嘛的？能刪除嗎？

    // split vendor js into its own file
    new webpack.optimize.CommonsChunkPlugin({
      name: 'vendor',
      minChunks: function (module) {
        // any required modules inside node_modules are extracted to vendor
        return (
          module.resource &&
          /\.js$/.test(module.resource) &&
          module.resource.indexOf(
            path.join(__dirname, '../node_modules')
          ) === 0
        )
      }
    }),
    // extract webpack runtime and module manifest to its own file in order to
    // prevent vendor hash from being updated whenever app bundle is updated
    new webpack.optimize.CommonsChunkPlugin({
      name: 'manifest',
      chunks: ['vendor']
    }),