title: Trouble with storybook in IE11. "WeakSet is not defined"
body: <p>I have a trouble with running storybook in IE11.
  This is the error that I see in IE11 console: <a href="https://i.stack.imgur.com/BJnuI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BJnuI.png" alt="enter image description here"></a></p>
  
  <p>I`m using core-js in babel like that:</p>
  
  <pre><code>presets: [
      ['@babel/preset-env', {
        modules: false,
        loose: true,
        useBuiltIns: "usage",
        corejs: 2,
        debug: true,
        targets: {
          browsers: [
            'last 2 Chrome versions',
            'last 2 Firefox versions',
            'last 2 Safari versions',
            'last 2 Opera versions',
            'last 2 Edge versions',
            'last 2 iOS versions',
            'last 2 ChromeAndroid versions',
            'IE 11'
          ]
        }
      }],
      '@babel/preset-react'
    ]
  </code></pre>
  
  <p>This is babel-loader in webpack:</p>
  
  <pre><code>{
    test: /\.jsx?$/,
    include: [resolve(__dirname, 'src')],
    exclude: /node_modules/,
    loader: 'babel-loader'
  }
  </code></pre>
  
  <p>Tryed it also with core-js@3.6.1, but I`ve got the same result.</p>
  
  <p>UPD: The translation of error: WeakSet is not defined.</p>