[FIX] web: properly hides submenu (ir_actions target=fullscreen)

This commit fixes the action target="fullscreen" in community, where
the submenu on the left would sometimes remain visible.

The fullscreen feature was added in commit : d65d251c57

addons/web/static/src/js/menu.js

@@ -160,12 +160,12 @@ var Menu = Widget.extend({
         $sub_menu.show();
 
         // Hide/Show the leftbar menu depending of the presence of sub-items
-        this.$secondary_menus.toggle(!!$sub_menu.children().length);
+        this.$secondary_menus.toggleClass('o_hidden', !$sub_menu.children().length);
 
         // Activate current menu item and show parents
         this.$secondary_menus.find('.active').removeClass('active');
         if ($main_menu !== $clicked_menu) {
-            $clicked_menu.parents().show();
+            $clicked_menu.parents().removeClass('o_hidden');
             if ($clicked_menu.is('.oe_menu_toggler')) {
                 $clicked_menu.toggleClass('oe_menu_opened').siblings('.oe_secondary_submenu:first').toggle();
             } else {