React dispatchEvent regression (v. 15.5.4)

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.5.4/react.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.5.4/react-dom.js"></script>
<div id="container"></div>

Babel + JSX

ReactDOM.render(
	<textarea id="textarea" onChange={alert} />,
  document.getElementById('container')
);

document.getElementById('textarea').dispatchEvent(new Event('input', { bubbles: true }));