Fix debbugs#20240 part two (jit-lock error during `comment-dwim').

jit-lock.el (jit-lock-after-change): Widen the buffer before
putting 'fontified text properties.

lisp/ChangeLog

+2015-04-04  Alan Mackenzie  <acm@muc.de>
+
+	Fix debbugs#20240 part two (jit-lock error during `comment-dwim').
+
+	* jit-lock.el (jit-lock-after-change): Widen the buffer before
+	putting 'fontified text properties.
+
 2015-04-03  Michael Albinus  <michael.albinus@gmx.de>
 
 	* net/tramp-cache.el (tramp-flush-file-property)

lisp/jit-lock.el

@@ -650,12 +650,14 @@ will take place when text is fontified stealthily."
     (let ((jit-lock-start start)
           (jit-lock-end end))
       (with-buffer-prepared-for-jit-lock
-          (run-hook-with-args 'jit-lock-after-change-extend-region-functions
-                              start end old-len)
-          ;; Make sure we change at least one char (in case of deletions).
-          (setq jit-lock-end (min (max jit-lock-end (1+ start)) (point-max)))
-          ;; Request refontification.
-          (put-text-property jit-lock-start jit-lock-end 'fontified nil))
+          (save-restriction
+	    (widen)
+	    (run-hook-with-args 'jit-lock-after-change-extend-region-functions
+				start end old-len)
+	    ;; Make sure we change at least one char (in case of deletions).
+	    (setq jit-lock-end (min (max jit-lock-end (1+ start)) (point-max)))
+	    ;; Request refontification.
+	    (put-text-property jit-lock-start jit-lock-end 'fontified nil)))
       ;; Mark the change for deferred contextual refontification.
       (when jit-lock-context-unfontify-pos
         (setq jit-lock-context-unfontify-pos