Revert "remove old markdown engine work-in-progress"

This reverts commit ee470b5317.

lib/pretty_text.rb

@@ -80,7 +80,11 @@ module PrettyText
     ctx_load(ctx, "#{Rails.root}/app/assets/javascripts/discourse-loader.js")
     ctx_load(ctx, "vendor/assets/javascripts/lodash.js")
     ctx_load_manifest(ctx, "pretty-text-bundle.js")
-    ctx_load_manifest(ctx, "markdown-it-bundle.js")
+
+    if SiteSetting.enable_experimental_markdown_it
+      ctx_load_manifest(ctx, "markdown-it-bundle.js")
+    end
+
     root_path = "#{Rails.root}/app/assets/javascripts/"
 
     apply_es6_file(ctx, root_path, "discourse/lib/utilities")
@@ -148,6 +152,13 @@ module PrettyText
         paths[:S3BaseUrl] = Discourse.store.absolute_base_url
       end
 
+      if SiteSetting.enable_experimental_markdown_it
+        # defer load markdown it
+        unless context.eval("window.markdownit")
+          ctx_load_manifest(context, "markdown-it-bundle.js")
+        end
+      end
+
       custom_emoji = {}
       Emoji.custom.map { |e| custom_emoji[e.name] = e.url }
 

lib/pretty_text/shims.js

@@ -7,6 +7,8 @@ __utils = require('discourse/lib/utilities');
 __emojiUnicodeReplacer = null;
 
 __setUnicode = function(replacements) {
+  require('pretty-text/engines/discourse-markdown/emoji').setUnicodeReplacements(replacements);
+
   let unicodeRegexp = new RegExp(Object.keys(replacements).sort().reverse().join("|"), "g");
 
   __emojiUnicodeReplacer = function(text) {