patch 8.1.1309: test for Normal highlight fails on MS-Windows GUI

Problem:    Test for Normal highlight fails on MS-Windows GUI.
Solution:   Skip the test for MS-Windows GUI.
diff --git a/src/testdir/test_highlight.vim b/src/testdir/test_highlight.vim
index 24379d6..7c6cc64 100644
--- a/src/testdir/test_highlight.vim
+++ b/src/testdir/test_highlight.vim
@@ -573,9 +573,12 @@
   call delete('Xtest_cursorline_with_visualmode')
 endfunc
 
+" This test must come before the Test_cursorline test, as it appears this
+" defines the Normal highlighting group anyway.
 func Test_1_highlight_Normalgroup_exists()
-  " This test must come before the Test_cursorline test, as it appears this
-  " defines the Normal highlighting group anyway.
-  let hlNormal = HighlightArgs('Normal')
-  call assert_match('hi Normal\s*clear', hlNormal)
+  " MS-Windows GUI sets the font
+  if !has('win32') || !has('gui_running')
+    let hlNormal = HighlightArgs('Normal')
+    call assert_match('hi Normal\s*clear', hlNormal)
+  endif
 endfunc