title: react-hot-loader with external configureStore throw "regeneratorRuntime is not defined" using redux-saga
body: <p>I'm adding react-hot-loader into my project. My project uses webpack2, babel7, react-hot-loader3 and webpack-dev-server. I got a "<strong>regeneratorRuntime is not defined</strong>" error when start the app. I use <a href="https://github.com/chentsulin/electron-react-boilerplate" rel="nofollow noreferrer">this boilerplate</a> as a sample.
  I'm not using the code below, because my configureStore is external, I don't have the access of my combined reducers(the store had applied redux-saga middleware).</p>
  
  <pre><code>if (module.hot) {
          module.hot.accept('../reducer', () =&gt;
              store.replaceReducer(require('../reducer')) // eslint-disable-line global-require
          );
      }
  </code></pre>
  
  <p>As I know, regeneratorRuntime is what babel to compile generator from es6 which is used by redux-saga, does this matter? How should I do when I couldn't make the store internal and can't access the reducers.</p>