title: Error with babel-polyfill and webpack
body: <p>I am following along a tutorial from Udemy, and we've just downloaded babel.
  Everything was working fine until I downloaded babel-polyfill and tried to integrate it. </p>
  
  <p>Currently this is my webpack and babelrc files: 
  <a href="https://i.stack.imgur.com/Lk3U7.jpg" rel="noreferrer">Webpack</a> &amp;
  <a href="https://i.stack.imgur.com/bJjlh.jpg" rel="noreferrer">Babel</a>
  and this is what the error looks like on the command line:
  <a href="https://i.stack.imgur.com/RVz6I.jpg" rel="noreferrer">Command Line Error</a>.</p>
  
  <p>Does anyone know what I'm doing wrong? Thanks in advance for all your help!</p>