Unbind M-o' and add new C-x x f' binding

* doc/lispref/modes.texi (Other Font Lock Variables):
`font-lock-fontify-block' is no longer bound.
* lisp/bindings.el (ctl-x-x-map): Bind `font-lock-update'.

* lisp/font-lock.el (font-lock-update): New command written by
Gregory Heytings <gregory@heytings.org>.

* lisp/loadup.el: Remove transitional experimental code.

doc/lispref/modes.texi

@@ -3247,8 +3247,7 @@ set by means of @var{other-vars} in @code{font-lock-defaults}
 @defvar font-lock-mark-block-function
 If this variable is non-@code{nil}, it should be a function that is
 called with no arguments, to choose an enclosing range of text for
-refontification for the command @kbd{M-o M-o}
-(@code{font-lock-fontify-block}).
+refontification for the command @kbd{M-x font-lock-fontify-block}.
 
 The function should report its choice by placing the region around it.
 A good choice is a range of text large enough to give proper results,

etc/NEWS

@@ -93,6 +93,10 @@ useful on systems such as FreeBSD which ships only with "etc/termcap".
 
 * Changes in Emacs 28.1
 
++++
+** New command 'font-lock-update', bound to 'C-x x f'.
+This command updates the syntax highlighting in this buffer.
+
 ** The new NonGNU ELPA archive is enabled by default alongside GNU ELPA.
 
 +++
@@ -2254,7 +2258,8 @@ first).
 Use 'M-x center-line' and 'M-x center-paragraph' instead.
 
 ** The 'M-o M-o' global binding have been removed.
-Use 'M-x font-lock-fontify-block' instead.
+Use 'M-x font-lock-fontify-block' instead, or the new `C-x x f'
+command, which toggles fontification in the current buffer.
 
 ** In 'f90-mode', the backslash character ('\') no longer escapes.
 For about a decade, the backslash character has no longer had a

lisp/bindings.el

@@ -1432,6 +1432,7 @@ if `inhibit-field-text-motion' is non-nil."
 
 (defvar ctl-x-x-map
   (let ((map (make-sparse-keymap)))
+    (define-key map "f" #'font-lock-update)
     (define-key map "g" #'revert-buffer)
     (define-key map "r" #'rename-buffer)
     (define-key map "u" #'rename-uniquely)

lisp/font-lock.el

@@ -1120,6 +1120,18 @@ portion of the buffer."
     (funcall font-lock-ensure-function
              (or beg (point-min)) (or end (point-max)))))
 
+(defun font-lock-update (&optional arg)
+  "Updates the syntax highlighting in this buffer.
+Refontify the accessible portion of this buffer, or enable Font Lock mode
+in this buffer if it is currently disabled.  With prefix ARG, toggle Font
+Lock mode."
+  (interactive "P")
+  (save-excursion
+    (if (and (not arg) font-lock-mode)
+        (font-lock-fontify-region (point-min) (point-max))
+      (font-lock-unfontify-region (point-min) (point-max))
+      (font-lock-mode 'toggle))))
+
 (defun font-lock-default-fontify-buffer ()
   "Fontify the whole buffer using `font-lock-fontify-region-function'."
   (let ((verbose (if (numberp font-lock-verbose)

lisp/loadup.el

@@ -477,29 +477,6 @@ lost after dumping")))
 (setq redisplay--inhibit-bidi nil)
 
 
-;; Experimental feature removal.
-(define-key global-map "\M-o" #'removed-facemenu-command)
-
-(defun removed-facemenu-command ()
-  "Transition command during test period for facemenu removal."
-  (interactive)
-  (switch-to-buffer "*Facemenu Removal*")
-  (let ((inhibit-read-only t))
-    (erase-buffer)
-    (insert-file-contents
-     (expand-file-name "facemenu-removal.txt" data-directory)))
-  (goto-char (point-min))
-  (special-mode))
-
-(defun facemenu-keymap-restore ()
-  "Restore the facemenu keymap."
-  ;; Global bindings:
-  (define-key global-map [C-down-mouse-2] 'facemenu-menu)
-  (define-key global-map "\M-o" 'facemenu-keymap)
-  (define-key facemenu-keymap "\eS" 'center-paragraph)
-  (define-key facemenu-keymap "\es" 'center-line)
-  (define-key facemenu-keymap "\M-o" 'font-lock-fontify-block))
-
 
 (if dump-mode
     (let ((output (cond ((equal dump-mode "pdump") "emacs.pdmp")