Add translate="no" to outgoing mentions and links (#25524)

lib/sanitize_ext/sanitize_config.rb

@@ -36,6 +36,11 @@ class Sanitize
       node['class'] = class_list.join(' ')
     end
 
+    TRANSLATE_TRANSFORMER = lambda do |env|
+      node = env[:node]
+      node.remove_attribute('translate') unless node['translate'] == 'no'
+    end
+
     UNSUPPORTED_HREF_TRANSFORMER = lambda do |env|
       return unless env[:node_name] == 'a'
 
@@ -63,8 +68,8 @@ class Sanitize
       elements: %w(p br span a del pre blockquote code b strong u i em ul ol li),
 
       attributes: {
-        'a' => %w(href rel class),
-        'span' => %w(class),
+        'a' => %w(href rel class translate),
+        'span' => %w(class translate),
         'ol' => %w(start reversed),
         'li' => %w(value),
       },
@@ -80,6 +85,7 @@ class Sanitize
 
       transformers: [
         CLASS_WHITELIST_TRANSFORMER,
+        TRANSLATE_TRANSFORMER,
         UNSUPPORTED_ELEMENTS_TRANSFORMER,
         UNSUPPORTED_HREF_TRANSFORMER,
       ]