bug#2551: 23.0.91; doc-view: split window only updated with scroll-bar-mode

With p.ps from:

   http://www.logic.at/prolog/p.ps

when I do:

   $ emacs -Q p.ps

and press:

   M-x scroll-bar-mode RET

   C-c C-c C-x 2

then the other window displays the PostScript text instead of the
image that it immediately shows when scroll-bar-mode is left on.


In GNU Emacs 23.0.91.1 (i386-apple-darwin8.11.1, GTK+ Version 2.12.9)
 of 2009-03-01 on mt-computer.local
Windowing system distributor `The XFree86 Project, Inc', version 11.0.40400000
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_GB.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t