patch 8.1.1193: typos and small problems in test files

Problem:    Typos and small problems in test files.
Solution:   Small improvements.
diff --git a/src/testdir/test_vartabs.vim b/src/testdir/test_vartabs.vim
index 0d14aad..df61c0e 100644
--- a/src/testdir/test_vartabs.vim
+++ b/src/testdir/test_vartabs.vim
@@ -5,6 +5,7 @@
 endif
 
 source view_util.vim
+
 func s:compare_lines(expect, actual)
   call assert_equal(join(a:expect, "\n"), join(a:actual, "\n"))
 endfunc
@@ -372,3 +373,9 @@
   call assert_fails('set vts=,8')
   call assert_fails('set vsts=,8')
 endfunc
+
+func Test_vartabs_reset()
+  set vts=8
+  set all&
+  call assert_equal('', &vts)
+endfunc