React dispatchEvent regression (v. 15.6.1)

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.6.1/react.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.6.1/react-dom.js"></script>
<div id="container"></div>

Babel + JSX

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

const textarea = document.getElementById('textarea');

textarea.value = 'yo!';
textarea.dispatchEvent(new Event('input', { bubbles: true }));

textarea.value = 'yo again!';
textarea.dispatchEvent(new Event('input', { bubbles: true }));