**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.nodeType !== COMMENT_NODE
      ) {
        const hostInstance = DOMRenderer.findHostInstanceWithNoPortals(
          container._reactRootContainer._internalRoot.current,
        );
        if (hostInstance) {
          warning(
            hostInstance.parentNode === container,
            'render(...): It looks like the React-rendered content of this ' +
              'container was removed without using React. This is not ' +
              'supported and will cause errors. Instead, call ' +
              'ReactDOM.unmountComponentAtNode to empty a container.',
          );
        }
      }
      const isRootRenderedBySomeReact = !!container._reactRootContainer;
      const rootEl = getReactRootElementInContainer(container);
      const hasNonRootReactChild = !!(
        rootEl && ReactDOMComponentTree.getInstanceFromNode(rootEl)
      );
      warning(
        !hasNonRootReactChild || isRootRenderedBySomeReact,
        'render(...): Replacing React-rendered children with a new root ' +
          'component. If you intended to update the children of this node, ' +
          'you should instead have the existing children update their state ' +
          'and render the new components instead of calling ReactDOM.render.',
      );
      warning(
        container.nodeType !== ELEMENT_NODE ||
          !((container: any): Element).tagName ||