patch 8.1.1953: more functions can be used as a method

Problem:    More functions can be used as a method.
Solution:   Allow more functions to be used as a method.
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 1352eaa..2ffdc24 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -1069,7 +1069,7 @@
 
 func Test_hlexists()
   call assert_equal(0, hlexists('does_not_exist'))
-  call assert_equal(0, hlexists('Number'))
+  call assert_equal(0, 'Number'->hlexists())
   call assert_equal(0, highlight_exists('does_not_exist'))
   call assert_equal(0, highlight_exists('Number'))
   syntax on
@@ -1102,7 +1102,7 @@
 func Test_inputlist()
   call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>1\<cr>", 'tx')
   call assert_equal(1, c)
-  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>2\<cr>", 'tx')
+  call feedkeys(":let c = ['Select color:', '1. red', '2. green', '3. blue']->inputlist()\<cr>2\<cr>", 'tx')
   call assert_equal(2, c)
   call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>3\<cr>", 'tx')
   call assert_equal(3, c)
@@ -1279,7 +1279,7 @@
   let g:regs = []
   func TestFunc() abort
     let g:regs += [reg_executing()]
-    let g:typed = input('?')
+    let g:typed = '?'->input()
     let g:regs += [reg_executing()]
   endfunc
   call feedkeys("@qy\<CR>", 'xt')
@@ -1295,6 +1295,25 @@
   unlet s:reg_stat
 endfunc
 
+func Test_inputsecret()
+  map W :call TestFunc()<CR>
+  let @q = "W"
+  let g:typed1 = ''
+  let g:typed2 = ''
+  let g:regs = []
+  func TestFunc() abort
+    let g:typed1 = '?'->inputsecret()
+    let g:typed2 = inputsecret('password: ')
+  endfunc
+  call feedkeys("@qsomething\<CR>else\<CR>", 'xt')
+  call assert_equal("something", g:typed1)
+  call assert_equal("else", g:typed2)
+  delfunc TestFunc
+  unmap W
+  unlet g:typed1
+  unlet g:typed2
+endfunc
+
 func Test_libcall_libcallnr()
   if !has('libcall')
     return