Add asset_host to Rails2Compatibility

actionpack/lib/action_controller/new_base/compatibility.rb

@@ -56,6 +56,12 @@ module ActionController
 
       cattr_accessor :consider_all_requests_local
       self.consider_all_requests_local = true
+
+      # Prepends all the URL-generating helpers from AssetHelper. This makes it possible to easily move javascripts, stylesheets,
+      # and images to a dedicated asset server away from the main web server. Example:
+      #   ActionController::Base.asset_host = "http://assets.example.com"
+      @@asset_host = ""
+      cattr_accessor :asset_host
     end
     
     # For old tests