patch 8.2.4204: screenpos() has non-zero row for invisible text

Problem:    screenpos() has non-zero row for invisible text.
Solution:   Only add the window row when the text is visible. (closes #9618)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4204,
 /**/
     4203,
 /**/