patch 9.0.0828: various typos

Problem:    Various typos.
Solution:   Correct typos. (closes #11432)
diff --git a/src/testdir/test_visual.vim b/src/testdir/test_visual.vim
index c6f80aa..573a2cf 100644
--- a/src/testdir/test_visual.vim
+++ b/src/testdir/test_visual.vim
@@ -1289,7 +1289,7 @@
 endfunc
 
 func Test_visual_block_ctrl_w_f()
-  " Emtpy block selected in new buffer should not result in an error.
+  " Empty block selected in new buffer should not result in an error.
   au! BufNew foo sil norm f
   edit foo