Fix crash during debugging React Native apps.

[MrMYHuang]

While I am debugging JS codes (by Visual Studio Code 1.19.1) of my React Native Windows app through RN packager, I get this error message:

This is my package.json.

  "dependencies": {
    "axios": "^0.17.1",
    "babel-core": "^7.0.0-beta.3",
    "buffer": "^5.0.8",
    "cheerio-without-node-native": "^0.20.2",
    "iconv-lite": "^0.4.19",
    "react": "16.0.0",
    "react-native": "~0.51.0",
    "react-native-code-push": "^5.2.1",
    "react-native-windows": "^0.51.0-rc.0",
    "react-navigation": "^1.0.0-beta.22",
    "react-redux": "^5.0.6",
    "react-test-renderer": "16.2.0",
    "redux": "^3.7.2",
    "redux-logger": "^3.0.6",
    "redux-promise-middleware": "^5.0.0",
    "redux-thunk": "^2.2.0",
    "stream": "^0.0.2"
  },

I guess the React Native environment needs not the extension for Node at the 132-th line in node_modules/iconv-lite/lib/index.js. Thus, I use the variable, navigator, to exclude the React Native environment...
Now, I can correctly launch my React Native apps in debugging mode.