Fix backspace issue where focus is lost from the textarea

On Chrome (v30) for Mac, there is an issue where if the textarea has grown, and the user then hits backspace, then their focus will be lost from the area (So if for example they hit backspace twice after a grow has occurred, the first will delete a character, but the second will trigger "Back" in the browser)

It seems to be the clone that causes this, and explicitly setting the focus to the real box again fixes the issue.