patch 8.1.1826: tests use hand coded feature and option checks

Problem:    Tests use hand coded feature and option checks.
Solution:   Use the commands from check.vim in more tests.
diff --git a/src/testdir/test_popup.vim b/src/testdir/test_popup.vim
index b25108c..e7b4c72 100644
--- a/src/testdir/test_popup.vim
+++ b/src/testdir/test_popup.vim
@@ -2,6 +2,7 @@
 
 source shared.vim
 source screendump.vim
+source check.vim
 
 let g:months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']
 let g:setting = ''
@@ -663,9 +664,9 @@
 endfunc
 
 func Test_popup_and_window_resize()
-  if !has('terminal') || has('gui_running')
-    return
-  endif
+  CheckFeature terminal
+  CheckNotGui
+
   let h = winheight(0)
   if h < 15
     return
@@ -918,9 +919,9 @@
 endfunc
 
 func Test_menu_only_exists_in_terminal()
-  if !exists(':tlmenu') || has('gui_running')
-    return
-  endif
+  CheckCommand tlmenu
+  CheckNotGui
+
   tlnoremenu  &Edit.&Paste<Tab>"+gP  <C-W>"+
   aunmenu *
   try