ox-html.el (org-html-display-buffer-mode): Delete

* ox-html.el (org-html-display-buffer-mode): Delete.
(org-html-export-as-html): Use `set-auto-mode' instead of
`org-html-display-buffer-mode'.

Thanks to Jambunathan for suggesting this.

lisp/ox-html.el

@@ -1125,16 +1125,6 @@ CSS classes, then this prefix can be very useful."
   :group 'org-export-html
   :type 'string)
 
-(defcustom org-html-display-buffer-mode 'html-mode
-  "Default mode when visiting the HTML output."
-  :group 'org-export-html
-  :version "24.4"
-  :package-version '(Org . "8.0")
-  :type '(choice (function 'html-mode)
-		 (function 'nxml-mode)
-		 (function :tag "Other mode")))
-
-
 
 ;;; Internal Functions
 
@@ -3108,14 +3098,14 @@ is non-nil."
 	      (erase-buffer)
 	      (insert output)
 	      (goto-char (point-min))
-	      (funcall org-html-display-buffer-mode)
+	      (set-auto-mode t)
 	      (org-export-add-to-stack (current-buffer) 'html)))
 	`(org-export-as 'html ,subtreep ,visible-only ,body-only ',ext-plist))
     (let ((outbuf (org-export-to-buffer
 		   'html "*Org HTML Export*"
 		   subtreep visible-only body-only ext-plist)))
       ;; Set major mode.
-      (with-current-buffer outbuf (funcall org-html-display-buffer-mode))
+      (with-current-buffer outbuf (set-auto-mode t))
       (when org-export-show-temporary-export-buffer
 	(switch-to-buffer-other-window outbuf)))))