[react-source] Use production build according to React::Config

Author: zetachang

lib/react/react-source.rb

@@ -4,13 +4,17 @@
       "Warning: `react/react-source` is deprecated, ",
       "use `react/react-source-browser` or `react/react-source-server` instead."
     ]
-    console.error(ms.join("")); 
+    console.error(ms.join(""));
   }
   require 'react.js'
   require "react-server.js"
 else
+  require "react/config"
   require "react/rails/asset_variant"
-  react_directory = React::Rails::AssetVariant.new(addons: true).react_directory
+  react_directory = React::Rails::AssetVariant.new(
+    addons: true,
+    variant: React::Config.config[:environment].to_sym
+  ).react_directory
   Opal.append_path react_directory.untaint
   Opal.append_path File.expand_path('../../react-sources/', __FILE__).untaint
 end