node_modules/optimize-css-assets-webpack-plugin/.babelrc

{
  "presets": [
    [
      "env",
      {
        "useBuiltIns": true,
        "targets": {
          "node": "current"
        },
        "exclude": [
          "transform-async-to-generator",
          "transform-regenerator"
        ]
      }
    ]
  ],
  "plugins": [
    [
      "transform-object-rest-spread",
      {
        "useBuiltIns": true
      }
    ]
  ]
}