title: Do I need to import core-js/stable and regenerator-runtime/runtime when using @babel/preset-env with useBuiltIns:'usage'?
body: <p>I use babel <code>7.8.3</code> together with <code>@babel/preset-env</code>, <code>useBuiltIns: 'usage'</code> and <code>corejs: 3</code>. The documentation for <code>@babel/preset-env</code> is not clear to me. </p>
  
  <p>Do I need to add the following lines at the top of my entry file or is it done automatically by babel?</p>
  
  <pre><code>import 'core-js/stable';
  import 'regenerator-runtime/runtime';
  </code></pre>