Bug 228319 Use contrasting colours for menulist separators r=timeless sr=jag

themes/classic/global/win/menu.css

@@ -277,7 +277,6 @@ menuseparator {
 menulist > menupopup > menuseparator,
 .menulist-menupopup > menuseparator {
   margin: 2px 0;
-  border-top: 1px solid #000000;
   border-bottom: none;
 }
 

themes/modern/global/menu.css

@@ -231,7 +231,6 @@ menuseparator {
 menulist > menupopup > menuseparator,
 .menulist-menupopup > menuseparator {
   margin: 2px 0;
-  border-top: 1px solid #000000;
   border-bottom: none;
 }