**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
((container: any): Element).tagName.toUpperCase() !== 'BODY',
        'render(): Rendering components directly into document.body is ' +
          'discouraged, since its children are often manipulated by third-party ' +
          'scripts and browser extensions. This may lead to subtle ' +
          'reconciliation issues. Try rendering into a container element created ' +
          'for your app.',
      );
    }
  };
  warnOnInvalidCallback = function(callback: mixed, callerName: string) {
    warning(
      callback === null || typeof callback === 'function',
      '%s(...): Expected the last optional `callback` argument to be a ' +
        'function. Instead received: %s.',
      callerName,
      callback,
    );
  };
}
ReactControlledComponent.injection.injectFiberControlledHostComponent(
  ReactDOMFiberComponent,
);
type DOMContainer =
  | (Element & {
      _reactRootContainer: ?Root,
    })
  | (Document & {
      _reactRootContainer: ?Root,
    });
type Container = Element | Document;