title: Check which JS module needs to be transpiled with Babel
body: <p>I'm using Webpack + Babel, but transpiling <code>node_modules</code> throws lots of errors, even if I try to exclude specific modules. I think a better approach would be to figure out which modules won't work in older browsers and only transpile those modules. Is there an easy way to do this?</p>
  
  <p>Ideally, I'd be able to compare a file produced by Webpack with a <code>browserslistrc</code> file and see which modules would cause the output to not be compatible with the browsers in <code>browserslistrc</code>.</p>