Restore Emacs 23 handling of display-buffer's BUFFER-OR-NAME argument.

* window.el (window-normalize-buffer-to-display): Remove.
(display-buffer): Handle buffer-or-name argument as in Emacs 23.

lisp/ChangeLog

+2011-12-20  Martin Rudalics  <rudalics@gmx.at>
+
+	* window.el (window-normalize-buffer-to-display): Remove.
+	(display-buffer): Handle buffer-or-name argument as in Emacs 23.
+
 2011-12-19  Chong Yidong  <cyd@gnu.org>
 
 	* vc/vc-dir.el (vc-dir-parent-marked-p, vc-dir-children-marked-p):

lisp/window.el

@@ -4526,19 +4526,6 @@ Return WINDOW."
 The actual non-nil value of this variable will be copied to the
 `window-dedicated-p' flag.")
 
-(defun window-normalize-buffer-to-display (buffer-or-name)
-  "Normalize BUFFER-OR-NAME argument for buffer display functions.
-If BUFFER-OR-NAME is nil, return the current buffer.  Else, if a
-buffer specified by BUFFER-OR-NAME exists, return that buffer.
-If no such buffer exists, create a buffer with the name
-BUFFER-OR-NAME and return that buffer."
-  (if buffer-or-name
-      (or (get-buffer buffer-or-name)
-	  (let ((buffer (get-buffer-create buffer-or-name)))
-	    (set-buffer-major-mode buffer)
-	    buffer))
-    (current-buffer)))
-
 (defconst display-buffer--action-function-custom-type
   '(choice :tag "Function"
 	   (const :tag "--" ignore) ; default for insertion
@@ -4640,7 +4627,7 @@ specified, e.g. by the user options `display-buffer-alist' or
   "A `display-buffer' action for displaying in another frame.")
 (put 'display-buffer--other-frame-action 'risky-local-variable t)
 
-(defun display-buffer (&optional buffer-or-name action frame)
+(defun display-buffer (buffer-or-name &optional action frame)
   "Display BUFFER-OR-NAME in some window, without selecting it.
 BUFFER-OR-NAME must be a buffer or the name of an existing
 buffer.  Return the window chosen for displaying BUFFER-OR-NAME,
@@ -4688,7 +4675,9 @@ search for a window that is already displaying the buffer.  See
 `display-buffer-reuse-window'."
   (interactive (list (read-buffer "Display buffer: " (other-buffer))
 		     (if current-prefix-arg t)))
-  (let ((buffer (window-normalize-buffer-to-display buffer-or-name))
+  (let ((buffer (if (bufferp buffer-or-name)
+		    buffer-or-name
+		  (get-buffer buffer-or-name)))
 	;; Handle the old form of the first argument.
 	(inhibit-same-window (and action (not (listp action)))))
     (unless (listp action) (setq action nil))