patch 9.0.0995: padding before virtual text is highlighted

Problem:    Padding before virtual text below is highlighted when 'number' and
            'nowrap' are set.
Solution:   Save and restore n_attr_skip. (closes #11643)
diff --git a/src/testdir/test_textprop.vim b/src/testdir/test_textprop.vim
index 1d43703..6493aef 100644
--- a/src/testdir/test_textprop.vim
+++ b/src/testdir/test_textprop.vim
@@ -2747,6 +2747,9 @@
   call term_sendkeys(buf, ":set number\<CR>")
   call VerifyScreenDump(buf, 'Test_prop_below_after_empty_2', {}) 
 
+  call term_sendkeys(buf, ":set nowrap\<CR>")
+  call VerifyScreenDump(buf, 'Test_prop_below_after_empty_3', {}) 
+
   call StopVimInTerminal(buf)
 endfunc