title: Can't find variable: Symbol
body: <p>I'm using create-react-native-app with expo's react-native v22.0.1. I've developed my app using the emulator, where it works properly. However, when I open it with the Expo app, I get a "Can't find variable: Symbol" error, occurring in <em>assembleStyles</em> (<strike>I've got no idea what that is</strike> that's just a function from the ansi-styles library, probably the error happens somewhere else).</p>
  
  <p>I've tried importing babel-polyfill or es6-symbol to the first line of my App.js file (entrypoint), but with no success.</p>
  
  <p>What can be going on here?</p>
  
  <p>Edit: these are my dependencies</p>
  
  <pre><code>"devDependencies": {
      "babel-cli": "^6.26.0",
      "babel-plugin-module-resolver": "^2.7.1",
      "babel-plugin-transform-class-properties": "6.24.1",
      "babel-plugin-transform-require-ignore": "^0.1.1",
      "babel-preset-env": "^1.6.1",
      "babel-preset-react-native": "^4.0.0",
      "chai": "^4.1.1",
      "chai-enzyme": "0.8.0",
      "cross-env": "^5.1.0",
      "enzyme": "3.1.0",
      "ignore-styles": "5.0.1",
      "jest-expo": "22.0.0",
      "node-sass": "4.5.3",
      "npm-run-all": "4.1.1",
      "react-addons-test-utils": "15.6.2",
      "react-native-scripts": "^1.5.0",
      "react-scripts": "^1.0.14",
      "react-test-renderer": "16.0.0",
      "sw-precache": "5.2.0",
      "watchman": "^0.1.8"
    },
    "dependencies": {
      "babel-plugin-remove-nonjs": "0.1.1",
      "babel-plugin-transform-inline-environment-variables": "^0.2.0",
      "expo": "^22.0.0",
      "nodemon": "^1.12.1",
      "prop-types": "15.6.0",
      "qs": "6.5.1",
      "react": "16.0.0-beta.5",
      "react-dom": "16.0.0",
      "react-facebook-login": "3.6.2",
      "react-google-login": "^3.0.1",
      "react-helmet": "5.2.0",
      "react-images": "^0.5.11",
      "react-native":
        "https://github.com/expo/react-native/archive/sdk-22.0.1.tar.gz",
      "react-native-keyboard-spacer": "^0.4.1",
      "react-native-snap-carousel": "^3.3.4",
      "react-redux": "^5.0.6",
      "react-router-dom": "^4.2.0",
      "react-router-native": "^4.2.0",
      "react-slick": "0.15.4",
      "redux": "^3.7.2",
      "redux-thunk": "2.2.0",
      "slick-carousel": "^1.8.1",
      "styled-components": "^2.2.1"
    }
  </code></pre>