patch 9.0.0828: various typos

Problem:    Various typos.
Solution:   Correct typos. (closes #11432)
diff --git a/src/testdir/test_expr.vim b/src/testdir/test_expr.vim
index e1fed36..6d6efe7 100644
--- a/src/testdir/test_expr.vim
+++ b/src/testdir/test_expr.vim
@@ -35,7 +35,7 @@
   call assert_true(has('patch-6.9.999'))
   call assert_true(has('patch-7.1.999'))
   call assert_true(has('patch-7.4.123'))
-  call assert_true(has('patch-7.4.123 ')) " Traling space can be allowed.
+  call assert_true(has('patch-7.4.123 ')) " Trailing space can be allowed.
 
   call assert_false(has('patch-7'))
   call assert_false(has('patch-7.4'))