patch 8.1.0711: test files still use function!

Problem:    Test files still use function!.
Solution:   Remove the exclamation mark.  Fix overwriting a function.
diff --git a/src/testdir/test_highlight.vim b/src/testdir/test_highlight.vim
index 1e8efea..67c7506 100644
--- a/src/testdir/test_highlight.vim
+++ b/src/testdir/test_highlight.vim
@@ -38,15 +38,15 @@
   call assert_fails("hi Crash term='asdf", "E475:")
 endfunc
 
-function! HighlightArgs(name)
+func HighlightArgs(name)
   return 'hi ' . substitute(split(execute('hi ' . a:name), '\n')[0], '\<xxx\>', '', '')
-endfunction
+endfunc
 
-function! IsColorable()
+func IsColorable()
   return has('gui_running') || str2nr(&t_Co) >= 8
-endfunction
+endfunc
 
-function! HiCursorLine()
+func HiCursorLine()
   let hiCursorLine = HighlightArgs('CursorLine')
   if has('gui_running')
     let guibg = matchstr(hiCursorLine, 'guibg=\w\+')
@@ -57,9 +57,9 @@
     let hi_bg = 'hi CursorLine cterm=NONE ctermbg=Gray'
   endif
   return [hiCursorLine, hi_ul, hi_bg]
-endfunction
+endfunc
 
-function! Check_lcs_eol_attrs(attrs, row, col)
+func Check_lcs_eol_attrs(attrs, row, col)
   let save_lcs = &lcs
   set list
 
@@ -67,7 +67,7 @@
 
   set nolist
   let &lcs = save_lcs
-endfunction
+endfunc
 
 func Test_highlight_eol_with_cursorline()
   let [hiCursorLine, hi_ul, hi_bg] = HiCursorLine()