Fix DashboardHelper reference in spec
Helpers::DashboardHelper
doesn't actually exist, and Ruby 2.5 gets rid
of the automatic top-level constant lookup (https://bugs.ruby-lang.org/issues/11547).
Helpers::DashboardHelper
doesn't actually exist, and Ruby 2.5 gets rid
of the automatic top-level constant lookup (https://bugs.ruby-lang.org/issues/11547).