patch 8.2.4739: accessing freed memory after WinScrolled autocmd event

Problem:    Accessing freed memory after WinScrolled autocmd event.
Solution:   Check the window pointer is still valid. (closes #10156)
            Remove the argument from may_trigger_winscrolled().
diff --git a/src/window.c b/src/window.c
index 1eab3dc..c9526a1 100644
--- a/src/window.c
+++ b/src/window.c
@@ -2784,9 +2784,13 @@
     recursive = FALSE;
 }
 
+/*
+ * Trigger WinScrolled for "curwin" if needed.
+ */
     void
-may_trigger_winscrolled(win_T *wp)
+may_trigger_winscrolled(void)
 {
+    win_T	    *wp = curwin;
     static int	    recursive = FALSE;
     char_u	    winid[NUMBUFLEN];
 
@@ -2804,10 +2808,14 @@
 	apply_autocmds(EVENT_WINSCROLLED, winid, winid, FALSE, wp->w_buffer);
 	recursive = FALSE;
 
-	wp->w_last_topline = wp->w_topline;
-	wp->w_last_leftcol = wp->w_leftcol;
-	wp->w_last_width = wp->w_width;
-	wp->w_last_height = wp->w_height;
+	// an autocmd may close the window, "wp" may be invalid now
+	if (win_valid_any_tab(wp))
+	{
+	    wp->w_last_topline = wp->w_topline;
+	    wp->w_last_leftcol = wp->w_leftcol;
+	    wp->w_last_width = wp->w_width;
+	    wp->w_last_height = wp->w_height;
+	}
     }
 }