laravel-mix 1.0
参考 https://github.com/mishoo/UglifyJS2/issues/3274
解决方案：
//node_modules\laravel-mix\src\config.js
uglify: {
sourceMap: true,
uglifyOptions: {
compress: {
warnings: false,
collapse_vars: false,//添加这一行
},
output: {
comments: false
}
}
},
