onBeforeInput fires after browser updates the DOM for special characters like "中" or 😣on Firefox and Edge

<!-- Note: if the issue is about documentation or the website, please file it at: https://github.com/reactjs/reactjs.org/issues/new --> **Do you want to request a *feature* or report a *bug*?** Bug **What is the current behavior?** onBeforeInput fires after browser updates the DOM for special characters like "中" or 😣on Firefox and Edge https://codesandbox.io/s/modest-franklin-muirj NOTE: pasting it would not trigger the bug, you have to type it in. You can use control-command-space to open the emoji keyboard on mac **What is the expected behavior?** DOM should not update before onBeforeInput fires **Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?** React: 16.3.1 Firefox: 68.0.1 Mac: 10.14.5