message: Update uglifyjs-webpack-plugin
diff: "cross-env": "^5.0.5",
  "dot-json": "^1.0.3",
  "npm-run-all": "^4.1.1",
  - "uglifyjs-webpack-plugin": "^1.0.0-beta.1",
  + "uglifyjs-webpack-plugin": "^1.1.2",
  "webext": "^1.9.1-with-submit.1",
  "webpack": "^3.7.1",
  "xo": "*"
  