Reuse existing milestones counting.

app/services/milestones/group_service.rb

@@ -44,11 +44,11 @@ module Milestones
     end
 
     def open_items_count
-      open_issues_count.merge(open_mr_count){ |title,issue,mr| issue + mr }
+      @project_milestones.merge(@project_milestones){ |title, milestone| milestone.map{|m| m.open_items_count }.sum }
     end
 
     def closed_items_count
-      closed_issues_count.merge(close_mr_count){ |title,issue,mr| issue + mr }
+      @project_milestones.merge(@project_milestones){ |title, milestone| milestone.map{|m| m.closed_items_count }.sum }
     end
 
     def total_items_count

app/views/groups/milestones/index.html.haml

 %h3.page-title
   Milestones
-  %span.pull-right milestones
+  %span.pull-right #{@group_milestones.titles.count} milestones
 
 %p.light
   Only milestones from

app/views/layouts/nav/_group.html.haml

@@ -13,10 +13,8 @@
       - if current_user
         %span.count= current_user.cared_merge_requests.opened.of_group(@group).count
   = nav_link(path: 'groups#milestones') do
-    = link_to merge_requests_group_path(@group) do
+    = link_to group_milestones_path(@group) do
       Milestones
-      - if current_user
-        %span.count= current_user.cared_merge_requests.opened.of_group(@group).count
   = nav_link(path: 'groups#members') do
     = link_to "Members", members_group_path(@group)