Merge branch 'pravi/gitlab-ce-update-html-pipeline' into 'master'

update html-pipeline 2.7.1 -> 2.8

Closes #48571

See merge request gitlab-org/gitlab-ce!20348

Gemfile

@@ -132,7 +132,7 @@ gem 'unf', '~> 0.1.4'
 gem 'seed-fu', '~> 2.3.7'
 
 # Markdown and HTML processing
-gem 'html-pipeline', '~> 2.7.1'
+gem 'html-pipeline', '~> 2.8'
 gem 'deckar01-task_list', '2.0.0'
 gem 'gitlab-markup', '~> 1.6.4'
 gem 'redcarpet', '~> 3.4'

Gemfile.lock

@@ -394,7 +394,7 @@ GEM
     hipchat (1.5.2)
       httparty
       mimemagic
-    html-pipeline (2.7.1)
+    html-pipeline (2.8.3)
       activesupport (>= 2)
       nokogiri (>= 1.4)
     html2text (0.2.0)
@@ -1061,7 +1061,7 @@ DEPENDENCIES
   hashie-forbidden_attributes
   health_check (~> 2.6.0)
   hipchat (~> 1.5.0)
-  html-pipeline (~> 2.7.1)
+  html-pipeline (~> 2.8)
   html2text
   httparty (~> 0.13.3)
   icalendar

Gemfile.rails5.lock

@@ -397,7 +397,7 @@ GEM
     hipchat (1.5.2)
       httparty
       mimemagic
-    html-pipeline (2.7.1)
+    html-pipeline (2.8.3)
       activesupport (>= 2)
       nokogiri (>= 1.4)
     html2text (0.2.0)
@@ -1071,7 +1071,7 @@ DEPENDENCIES
   hashie-forbidden_attributes
   health_check (~> 2.6.0)
   hipchat (~> 1.5.0)
-  html-pipeline (~> 2.7.1)
+  html-pipeline (~> 2.8)
   html2text
   httparty (~> 0.13.3)
   icalendar

lib/banzai/filter/sanitization_filter.rb

@@ -4,27 +4,20 @@ module Banzai
     #
     # Extends HTML::Pipeline::SanitizationFilter with a custom whitelist.
     class SanitizationFilter < HTML::Pipeline::SanitizationFilter
+      include Gitlab::Utils::StrongMemoize
+
       UNSAFE_PROTOCOLS = %w(data javascript vbscript).freeze
       TABLE_ALIGNMENT_PATTERN = /text-align: (?<alignment>center|left|right)/
 
       def whitelist
-        whitelist = super
-
-        customize_whitelist(whitelist)
-
-        whitelist
+        strong_memoize(:whitelist) do
+          customize_whitelist(super.dup)
+        end
       end
 
       private
 
-      def customized?(transformers)
-        transformers.last.source_location[0] == __FILE__
-      end
-
       def customize_whitelist(whitelist)
-        # Only push these customizations once
-        return if customized?(whitelist[:transformers])
-
         # Allow table alignment; we whitelist specific text-align values in a
         # transformer below
         whitelist[:attributes]['th'] = %w(style)