bug#18161: 24.3.92; Crash in do_switch_frame

[Eli Zaretskii]

> Date: Sat, 02 Aug 2014 18:40:59 +0100
> From: Mat Smiglarski <penthief@SDF.ORG>
> Cc: 18161@debbugs.gnu.org
> 
> Here is my .emacs and this should be enough to reproduce the segfault at 
> startup.
> 
> (winner-mode)
> (make-frame '((left . unbound-symbol)))

FWIW, I cannot reproduce the problem with this .emacs.  I get a
*Warnings* window saying

  Warning (initialization): An error occurred while loading `/foo/bar/.emacs':

  Wrong type argument: integerp, unbound-symbol

  To ensure normal operation, you should investigate and remove the
  cause of the error in your initialization file.  Start Emacs with
  the `--debug-init' option to view a complete error backtrace.