Separate prefix styles from non-item styles in menus

Change-Id: I98255ac8a2e173c1d1c3fef3806fa490526b54cb
diff --git a/dev/js/spec/menuSpec.js b/dev/js/spec/menuSpec.js
index c24a75b..664a5b9 100644
--- a/dev/js/spec/menuSpec.js
+++ b/dev/js/spec/menuSpec.js
@@ -476,7 +476,6 @@
         expect(menu.element().getElementsByTagName("li")[5]).toBe(undefined);
       });
 
-
       it('should be nextable', function () {
         var menu = KorAP.HintMenu.create("cnx/", list);
         menu._firstActive = true;
@@ -1498,6 +1497,7 @@
       it('should be initializable', function () {
         var p = prefixClass.create();
         expect(p.element().classList.contains('pref')).toBeTruthy();
+        expect(p.element().classList.contains('non-item')).toBeTruthy();
         expect(p.isSet()).not.toBeTruthy();
 
         /*
diff --git a/dev/js/src/menu/prefix.js b/dev/js/src/menu/prefix.js
index 3930e45..f6c6c76 100644
--- a/dev/js/src/menu/prefix.js
+++ b/dev/js/src/menu/prefix.js
@@ -18,6 +18,7 @@
 
     // Add prefix span
     t._el = document.createElement('span');
+    t._el.classList.add('non-item');
     t._el.classList.add('pref');
     // Connect action