patch 9.0.0304: WinScrolled is not triggered when only skipcol changes

Problem:    WinScrolled is not triggered when only skipcol changes.
Solution:   Add w_last_skipcol and use it. (closes #10998)

src/autocmd.c

@@ -1249,6 +1249,7 @@ do_autocmd_event(
 		{
 		    curwin->w_last_topline = curwin->w_topline;
 		    curwin->w_last_leftcol = curwin->w_leftcol;
+		    curwin->w_last_skipcol = curwin->w_skipcol;
 		    curwin->w_last_width = curwin->w_width;
 		    curwin->w_last_height = curwin->w_height;
 		}

src/structs.h

@@ -3542,9 +3542,10 @@ struct window_S
 				    // window
 #endif
 
-    // four fields that are only used when there is a WinScrolled autocommand
+    // five fields that are only used when there is a WinScrolled autocommand
     linenr_T	w_last_topline;	    // last known value for w_topline
     colnr_T	w_last_leftcol;	    // last known value for w_leftcol
+    colnr_T	w_last_skipcol;	    // last known value for w_skipcol
     int		w_last_width;	    // last known value for w_width
     int		w_last_height;	    // last known value for w_height
 

src/testdir/test_autocmd.vim

@@ -419,6 +419,39 @@ func Test_WinScrolled_close_curwin()
   call delete('Xtestout')
 endfunc
 
+func Test_WinScrolled_long_wrapped()
+  CheckRunVimInTerminal
+
+  let lines =<< trim END
+    set scrolloff=0
+    let height = winheight(0)
+    let width = winwidth(0)
+    let g:scrolled = 0
+    au WinScrolled * let g:scrolled += 1
+    call setline(1, repeat('foo', height * width))
+    call cursor(1, height * width)
+  END
+  call writefile(lines, 'Xtest_winscrolled_long_wrapped')
+  let buf = RunVimInTerminal('-S Xtest_winscrolled_long_wrapped', {'rows': 6})
+
+  call term_sendkeys(buf, ":echo g:scrolled\<CR>")
+  call WaitForAssert({-> assert_match('^0 ', term_getline(buf, 6))}, 1000)
+
+  call term_sendkeys(buf, 'gj')
+  call term_sendkeys(buf, ":echo g:scrolled\<CR>")
+  call WaitForAssert({-> assert_match('^1 ', term_getline(buf, 6))}, 1000)
+
+  call term_sendkeys(buf, '0')
+  call term_sendkeys(buf, ":echo g:scrolled\<CR>")
+  call WaitForAssert({-> assert_match('^2 ', term_getline(buf, 6))}, 1000)
+
+  call term_sendkeys(buf, '$')
+  call term_sendkeys(buf, ":echo g:scrolled\<CR>")
+  call WaitForAssert({-> assert_match('^3 ', term_getline(buf, 6))}, 1000)
+
+  call delete('Xtest_winscrolled_long_wrapped')
+endfunc
+
 func Test_WinClosed()
   " Test that the pattern is matched against the closed window's ID, and both
   " <amatch> and <afile> are set to it.

src/version.c

@@ -707,6 +707,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    304,
 /**/
     303,
 /**/

src/window.c

@@ -2806,6 +2806,7 @@ may_trigger_winscrolled(void)
 
     if (wp->w_last_topline != wp->w_topline
 	    || wp->w_last_leftcol != wp->w_leftcol
+	    || wp->w_last_skipcol != wp->w_skipcol
 	    || wp->w_last_width != wp->w_width
 	    || wp->w_last_height != wp->w_height)
     {
@@ -2820,6 +2821,7 @@ may_trigger_winscrolled(void)
 	{
 	    wp->w_last_topline = wp->w_topline;
 	    wp->w_last_leftcol = wp->w_leftcol;
+	    wp->w_last_skipcol = wp->w_skipcol;
 	    wp->w_last_width = wp->w_width;
 	    wp->w_last_height = wp->w_height;
 	}