Remove special handling for the `'` problem

While `escape_once` will create this HTML entity, Nokogiri always
translates it back before it gets to IssueReferenceFilter, so there
should be no danger of erroneous issue links.

lib/gitlab/markdown/merge_request_reference_filter.rb

@@ -64,7 +64,6 @@ module Gitlab
         end
       end
 
-      # TODO (rspeicher): Cleanup
       def url_for_merge_request(mr, project)
         h = Rails.application.routes.url_helpers
         h.namespace_project_merge_request_url(project.namespace, project, mr,

lib/redcarpet/render/gitlab_html.rb

@@ -13,17 +13,8 @@ class Redcarpet::Render::GitlabHTML < Redcarpet::Render::HTML
     super(options)
   end
 
-  # If project has issue number 39, apostrophe will be linked in
-  # regular text to the issue as Redcarpet will convert apostrophe to
-  # #39;
-  # We replace apostrophe with right single quote before Redcarpet
-  # does the processing and put the apostrophe back in postprocessing.
-  # This only influences regular text, code blocks are untouched.
   def normal_text(text)
-    return text unless text.present?
-
-    text = ERB::Util.html_escape_once(text)
-    text.gsub("'", "&rsquo;")
+    ERB::Util.html_escape_once(text)
   end
 
   # Stolen from Rugments::Plugins::Redcarpet as this module is not required
@@ -45,8 +36,6 @@ class Redcarpet::Render::GitlabHTML < Redcarpet::Render::HTML
   end
 
   def postprocess(full_document)
-    full_document.gsub!("&rsquo;", "'")
-
     unless @template.instance_variable_get("@project_wiki") || @project.nil?
       full_document = h.create_relative_links(full_document)
     end

spec/fixtures/markdown.md.erb

@@ -138,7 +138,6 @@ References should be parseable even inside _!<%= merge_request.iid %>_ emphasis.
 
 - Issue: #<%= issue.iid %>
 - Issue in another project: <%= xref %>#<%= xissue.iid %>
-- Ignores HTML entities: TODO:&#39;
 - Ignored in code: `#<%= issue.iid %>`
 - Ignored in links: [Link to #<%= issue.iid %>](#issue-link)