**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
const hostContextDev = ((hostContext: any): HostContextDev);
      validateDOMNesting(null, text, hostContextDev.ancestorInfo);
    }
    const textNode: TextInstance = createTextNode(text, rootContainerInstance);
    precacheFiberNode(internalInstanceHandle, textNode);
    return textNode;
  },
  now: ReactDOMFrameScheduling.now,
  mutation: {
    commitMount(
      domElement: Instance,
      type: string,
      newProps: Props,
      internalInstanceHandle: Object,
    ): void {
      ((domElement: any):
        | HTMLButtonElement
        | HTMLInputElement
        | HTMLSelectElement
        | HTMLTextAreaElement).focus();
    },
    commitUpdate(
      domElement: Instance,
      updatePayload: Array<mixed>,
      type: string,
      oldProps: Props,