Cleanup labels helper and fix prepending logic

This makes it easier to override this helper's
class methods in EE

app/helpers/labels_helper.rb

@@ -2,7 +2,6 @@
 
 module LabelsHelper
   extend self
-  include ActionView::Helpers::TagHelper
 
   def show_label_issuables_link?(label, issuables_type, current_user: nil)
     return true unless label.project_label?
@@ -64,8 +63,8 @@ module LabelsHelper
     # by LabelReferenceFilter
     span = %(<span class="badge color-label #{"has-tooltip" if tooltip}" ) +
       %(data-html="true" style="background-color: #{label.color}; color: #{text_color}" ) +
-      %(title="#{escape_once(title)}" data-container="body">) +
-      %(#{escape_once(label.name)}#{label_suffix}</span>)
+      %(title="#{ERB::Util.html_escape_once(title)}" data-container="body">) +
+      %(#{ERB::Util.html_escape_once(label.name)}#{label_suffix}</span>)
 
     span.html_safe
   end
@@ -247,9 +246,6 @@ module LabelsHelper
   def issuable_types
     ['issues', 'merge requests']
   end
-
-  # Required for Banzai::Filter::LabelReferenceFilter
-  module_function :render_colored_label, :text_color_for_bg, :escape_once, :label_tooltip_title
 end
 
 LabelsHelper.prepend_if_ee('EE::LabelsHelper')

ee/app/helpers/ee/labels_helper.rb

@@ -2,6 +2,12 @@
 
 module EE
   module LabelsHelper
+    extend ActiveSupport::Concern
+
+    prepended do
+      singleton_class.prepend self
+    end
+
     def render_label(label, tooltip: true, link: nil, css: nil, dataset: nil)
       content = super
       content = scoped_label_wrapper(content, label) if label.scoped_label?
@@ -13,18 +19,8 @@ module EE
       %(<span class="d-inline-block position-relative scoped-label-wrapper">#{link}#{scoped_labels_doc_link(label)}</span>).html_safe
     end
 
-    def scoped_labels_doc_link(label)
-      text_color = ::LabelsHelper.text_color_for_bg(label.color)
-      content = %(<i class="fa fa-question-circle" style="background-color: #{label.color}; color: #{text_color}"></i>)
-      help_url = ::Gitlab::Routing.url_helpers.help_page_url('user/project/labels.md', anchor: 'scoped-labels')
-
-      %(<a href="#{help_url}" class="label scoped-label" target="_blank" rel="noopener">#{content}</a>)
-    end
-
     def label_tooltip_title(label)
-      # can't use `super` because this is called also as a module method from
-      # banzai
-      tooltip = ::LabelsHelper.label_tooltip_title(label)
+      tooltip = super
       tooltip = %(<span class='font-weight-bold scoped-label-tooltip-title'>Scoped label</span><br />#{tooltip}) if label.scoped_label?
 
       tooltip
@@ -59,6 +55,14 @@ module EE
       super + ['epics']
     end
 
-    module_function :scoped_label_wrapper, :scoped_labels_doc_link, :label_tooltip_title
+    private
+
+    def scoped_labels_doc_link(label)
+      text_color = text_color_for_bg(label.color)
+      content = %(<i class="fa fa-question-circle" style="background-color: #{label.color}; color: #{text_color}"></i>)
+      help_url = ::Gitlab::Routing.url_helpers.help_page_url('user/project/labels.md', anchor: 'scoped-labels')
+
+      %(<a href="#{help_url}" class="label scoped-label" target="_blank" rel="noopener">#{content}</a>)
+    end
   end
 end

ee/lib/ee/banzai/filter/label_reference_filter.rb

@@ -13,14 +13,14 @@ module EE
 
           if label.scoped_label? && parent && parent.feature_available?(:scoped_labels)
             presenter = label.present(issuable_parent: parent)
-            content = ::EE::LabelsHelper.scoped_label_wrapper(content, presenter)
+            content = ::LabelsHelper.scoped_label_wrapper(content, presenter)
           end
 
           content
         end
 
         def tooltip_title(label)
-          ::EE::LabelsHelper.label_tooltip_title(label)
+          ::LabelsHelper.label_tooltip_title(label)
         end
       end
     end