title: Linter error - Browser-only function is not defined
body: <p>I'm relying on a class that is available in browser, <code>FileReader</code> </p>
  
  <p>I keep getting an error in webpack - <code>'FileReader' is not defined                  no-undef</code></p>
  
  <p>What is the correct way of dealing with this? I'm currently using a method where I just ignore the message.</p>