Move point at least 1 char in markdown-match-propertized-text

   `font-lock-fontify-keywords-region` expects the matcher to move the
   cursor forward and infloops otherwise.

   In markdown mode, on some occasions cached matched data at POS has
   end at (1- POS), which is strange but seems to be happening. Make
   sure that such anomalies don't infloop font-lock.

markdown-mode.el

@@ -2891,13 +2891,17 @@ Return nil otherwise."
 (defun markdown-match-propertized-text (property last)
   "Match text with PROPERTY from point to LAST.
 Restore match data previously stored in PROPERTY."
-  (let (saved pos)
-    (unless (setq saved (get-text-property (point) property))
+  (let ((saved (get-text-property (point) property))
+        pos)
+    (unless saved
       (setq pos (next-single-char-property-change (point) property nil last))
       (setq saved (get-text-property pos property)))
     (when saved
       (set-match-data saved)
-      (goto-char (min (1+ (match-end 0)) (point-max)))
+      ;; Step at least one character beyond point. Otherwise
+      ;; `font-lock-fontify-keywords-region' infloops.
+      (goto-char (min (1+ (max (match-end 0) (point)))
+                      (point-max)))
       saved)))
 
 (defun markdown-match-pre-blocks (last)