title: ExpectedConditions for a window not available
body: <p>Is there an api for waiting for a window to load before switching to it or the presence of a window title in the new window?
  We have ExpectedConditions.frameToBeAvailableAndSwitchToIt for a frame to be available, however, would make life easier if we had an equivalent one for a window as well.
  Any response would be much appreciated. Thanks.</p>