```ruby
module Polymer
  module Rails
    class Railtie < ::Rails::Railtie
      initializer :polymer_html_import do
        helpers = %q{ include AssetTagHelper }
        ::ActionView::Helpers::AssetTagHelper.module_eval(helpers)
        ::Rails.application.assets.context_class.class_eval(helpers)
      end

      initializer :precompile_polymer do |app|
        app.config.assets.precompile += %w( polymer/polymer.js )
      end

      initializer :add_preprocessors do |app|
        app.assets.register_mime_type "text/html", ".html"
        app.assets.register_preprocessor "text/html", Polymer::Rails::DirectiveProcessor
        app.assets.register_postprocessor 'text/html', :web do |context, data|
          Polymer::Rails::ComponentsProcessor.new(context, data).process
        end
      end

    end
  end
end
```

Fix html_import_tag helper in Rails 3
user
```ruby
module Polymer
  module Rails
    class Railtie < ::Rails::Railtie
      initializer :polymer_html_import do
        helpers = %q{ include AssetTagHelper }
        ::ActionView::Base.module_eval(helpers)
        ::Rails.application.assets.context_class.class_eval(helpers)
      end

      initializer :precompile_polymer do |app|
        app.config.assets.precompile += %w( polymer/polymer.js )
      end

      initializer :add_preprocessors do |app|
        app.assets.register_mime_type "text/html", ".html"
        app.assets.register_preprocessor "text/html", Polymer::Rails::DirectiveProcessor
        app.assets.register_postprocessor 'text/html', :web do |context, data|
          Polymer::Rails::ComponentsProcessor.new(context, data).process
        end
      end

    end
  end
end
```
assistant