Add tests for :func s:baz(a, b = 2, ...)

Author: Luma

test/test1.ok

@@ -3,6 +3,8 @@
   (return 0))
 (function (s:bar (a 1) (b 2) . ...)
   (return 0))
+(function (s:baz a (b 2) . ...)
+  (return 0))
 (if 1
   (echo "if 1")
  elseif 2

test/test1.vim

@@ -5,6 +5,9 @@ endfunction
 function s:bar(a = 1, b = 2, ...)
   return 0
 endfunction
+function s:baz(a, b = 2, ...)
+  return 0
+endfunction
 if 1
   echo "if 1"
 elseif 2