Bug: window as new portal will break event delegation

<!-- Please provide a clear and concise description of what the bug is. Include screenshots if needed. Please test using the latest version of the relevant React packages to make sure your issue has not already been fixed. --> React version: any? ## Steps To Reproduce 1. Button attach to a window portal with window.open 2. Event not triggering <!-- Your bug will get fixed much faster if we can run your code and it doesn't have dependencies other than React. Issues without reproduction steps or code examples may be immediately closed as not actionable. --> Link to code example: ```javascript const { useState, useEffect } = React; function WindowPortal({ children }) { const [container, setContainer] = useState(document.createElement('div')); useEffect(() => { const newWindow = window.open('', '', 'width=600,height=400,left=200,top=200'); newWindow.document.body.appendChild(container); }); return ReactDOM.createPortal(children, container); } function App() { const [value, setValue] = useState('unclicked'); const handleClick = () => setValue('clicked'); return ( <div> <div>Portal Test</div> <WindowPortal> <button onClick={handleClick}>{value}</button> </WindowPortal> </div> ); } ReactDOM.render( React.createElement(App), document.getElementById('root') ); ``` <!-- Please provide a CodeSandbox (https://codesandbox.io/s/new), a link to a repository on GitHub, or provide a minimal code example that reproduces the problem. You may provide a screenshot of the application if you think it is relevant to your bug report. Here are some tips for providing a minimal example: https://stackoverflow.com/help/mcve. --> Any event in the new window will not be triggered since all events are bind to the original window. I think react can support a new mode for using native event binding rather than event delegation if it makes sense. [Preact](https://github.com/preactjs/preact) actually uses native brow…