**Do you want to request a *feature* or report a *bug*?**
bug

**What is the current behavior?**
If there is a client/server mismatch for text inside of an a or button element, it causes it to be automatically focused on page load.

**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar (template for React 16: https://jsfiddle.net/Luktwrdm/, template for React 15: https://jsfiddle.net/hmbg7e9w/).**
```
let text;
let URL = '/randomURL';
if (typeof window !== 'undefined') {
  text = 'CLIENT TEXT';
} else {
  text = 'TEXT';
}

return (
  <a href={URL}>
    {text}
  </a>
);
```

if the focus is not on the window (i.e. if a dom element is selected in the chrome inspector or react inspector widnow), then it doesn't add the focus.

**What is the expected behavior?**
The expected behavior is that it would either show CLIENT TEXT or TEXT (depending on how React16 resolves the diff), but for it not to be automatically highlighted 

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
React16 / macosx / chrome + ff + safari
'Target container is not a DOM element.',
  );
  
  return ReactPortal.createPortal(children, container, null, key);
}
const ReactDOM: Object = {
  createPortal,
  findDOMNode(
    componentOrElement: Element | ?React$Component<any, any>,
  ): null | Element | Text {
    if (__DEV__) {
      let owner = (ReactCurrentOwner.current: any);
      if (owner !== null) {
        const warnedAboutRefsInRender =
          owner.stateNode._warnedAboutRefsInRender;
        warning(
          warnedAboutRefsInRender,
          '%s is accessing findDOMNode inside its render(). ' +
            'render() should be a pure function of props and state. It should ' +
            'never access something that requires stale data from the previous ' +
            'render, such as refs. Move this logic to componentDidMount and ' +
            'componentDidUpdate instead.',
          getComponentName(owner) || 'A component',
        );
        owner.stateNode._warnedAboutRefsInRender = true;
      }
    }
    if (componentOrElement == null) {
      return null;
    }