title: Import firebaseui with rollup
body: <p>I am trying to import the <a href="https://github.com/firebase/firebaseui-web" rel="nofollow noreferrer">firebaseui</a> library with rollup. The ui loads fine if I include firbaseui with the cdn they provide:</p>
  
  <pre><code>&lt;script src="https://www.gstatic.com/firebasejs/ui/4.5.0/firebase-ui-auth.js"&gt;&lt;/script&gt;
  &lt;link type="text/css" rel="stylesheet" href="https://www.gstatic.com/firebasejs/ui/4.5.0/firebase-ui-auth.css" /&gt;
  </code></pre>
  
  <p>but if I instead try to import it with <code>import * as firebaseui from 'firebaseui'</code> I get the following error in the browser: <code>Uncaught TypeError: Failed to resolve module specifier "firebaseui". Relative references must start with either "/", "./", or "../".</code></p>
  
  <p>I am using rollup's plugin-node-resolve and plugin-commonjs with this config:</p>
  
  <pre><code>import resolve from "@rollup/plugin-node-resolve";
  import commonjs from "@rollup/plugin-commonjs";
  
  export default {
    // If using any exports from a symlinked project, uncomment the following:
    // preserveSymlinks: true,
    input: ["src/index.js"],
    output: {
      file: "public/index.js",
      format: "es",
      sourcemap: true,
    },
    plugins: [resolve(), commonjs()],
  };
  </code></pre>
  
  <p>which I thought was meant to handle bare module errors like this, so I don't know how to fix this.</p>