Further empty <li> tweaks

* lisp/net/shr.el (shr-tag-li): When showing several empty
<li> elements, ensure that they really get inserted on a new line.

lisp/net/shr.el

@@ -1617,7 +1617,9 @@ The preference is a float determined from `shr-prefer-media-type'."
 	(put-text-property start (1+ start)
 			   'shr-continuation-indentation shr-indentation)
 	(put-text-property start (1+ start) 'shr-prefix-length (length bullet))
-	(shr-generic dom)))))
+	(shr-generic dom))))
+  (unless (bolp)
+    (insert "\n")))
 
 (defun shr-mark-fill (start)
   ;; We may not have inserted any text to fill.

test/data/shr/li-empty.html

@@ -0,0 +1 @@
+<ol><li></li><li></li><li></li></ol>

test/data/shr/li-empty.txt

@@ -0,0 +1,3 @@
+1 
+2 
+3