Add tooltip to branch delete button

app/views/projects/branches/_branch.html.haml

@@ -26,7 +26,7 @@
           Compare
 
       - if can_remove_branch?(@project, branch.name)
-        = link_to namespace_project_branch_path(@project.namespace, @project, branch.name), class: 'btn btn-grouped btn-xs btn-remove remove-row', method: :delete, data: { confirm: "Deleting the '#{branch.name}' branch cannot be undone. Are you sure?" }, remote: true do
+        = link_to namespace_project_branch_path(@project.namespace, @project, branch.name), class: 'btn btn-grouped btn-xs btn-remove remove-row has_tooltip', title: "Delete branch", method: :delete, data: { confirm: "Deleting the '#{branch.name}' branch cannot be undone. Are you sure?", container: 'body' }, remote: true do
           = icon("trash-o")
 
   - if commit