**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
if ((componentOrElement: any).nodeType === ELEMENT_NODE) {
      return (componentOrElement: any);
    }
    const inst = ReactInstanceMap.get(componentOrElement);
    if (inst) {
      return DOMRenderer.findHostInstance(inst);
    }
    if (typeof componentOrElement.render === 'function') {
      invariant(false, 'Unable to find node on an unmounted component.');
    } else {
      invariant(
        false,
        'Element appears to be neither ReactComponent nor DOMNode. Keys: %s',
        Object.keys(componentOrElement),
      );
    }
  },
  hydrate(element: React$Node, container: DOMContainer, callback: ?Function) {
    
    return legacyRenderSubtreeIntoContainer(
      null,
      element,
      container,
      true,
      callback,
    );
  },
  render(
    element: React$Element<any>,
    container: DOMContainer,