bug#21428: 24.5; Crash of emacs on OS X, installed via homebrew cask

[martin rudalics]

> However, I noticed that a number of NextStep callback functions start with
> the following code sequence:
>
>    if (!emacsframe->output_data.ns)
>      return;
>
> If `ns' is NULL it would account for the crash. I don't see why we can't
> add it to the windowDidResize: method as well.

I think we should put this into updateFrameSize at least.

martin