patch 8.2.4611: typos in tests; one lua line not covered by test

Problem:    Typos in tests; one lua line not covered by test.
Solution:   Fix typos. Add test case. (Dominique Pellé, closes #9994)
diff --git a/src/testdir/test_statusline.vim b/src/testdir/test_statusline.vim
index 28d8798..eaf1525 100644
--- a/src/testdir/test_statusline.vim
+++ b/src/testdir/test_statusline.vim
@@ -260,7 +260,7 @@
   call assert_match('^vimLineComment\s*$', s:get_statusline())
   syntax off
 
-  "%{%expr%}: evaluates enxpressions present in result of expr
+  "%{%expr%}: evaluates expressions present in result of expr
   func! Inner_eval()
     return '%n some other text'
   endfunc