message: Move Darwin-specific JS libs to optional
diff: "fetch-mock": "^7.0.0-alpha.6",
  "file-loader": "^1.1.11",
  "fork-ts-checker-webpack-plugin": "^0.4.9",
  - "fsevents": "^2.0.7",
  "ignore-styles": "^5.0.1",
  "imports-loader": "^0.7.1",
  "jest": "^24.8.0",
  "webpack-cli": "^3.1.1",
  "webpack-dev-server": "^3.1.14",
  "webpack-sources": "^1.1.0"
  + },
  + "optionalDependencies": {
  + "fsevents": "^2.0.7"
  }
  }
  