remove vestigial code

Looks like this was left over from converting Rails to Rack.  I think
it's safe to remove now.

actionpack/lib/action_controller/middleware.rb

-module ActionController
-  class Middleware < Metal
-    class ActionMiddleware
-      def initialize(controller, app)
-        @controller, @app = controller, app
-      end
-
-      def call(env)
-        request = ActionDispatch::Request.new(env)
-        @controller.build(@app).dispatch(:index, request)
-      end
-    end
-
-    class << self
-      alias build new
-
-      def new(app)
-        ActionMiddleware.new(self, app)
-      end
-    end
-
-    attr_internal :app
-
-    def process(action)
-      response = super
-      self.status, self.headers, self.response_body = response if response.is_a?(Array)
-      response
-    end
-
-    def initialize(app)
-      super()
-      @_app = app
-    end
-
-    def index
-      call(env)
-    end
-  end
-end
\ No newline at end of file

actionpack/test/controller/new_base/metal_test.rb

-require 'abstract_unit'
-
-module MetalTest
-  class MetalMiddleware < ActionController::Middleware
-    def call(env)
-      if env["PATH_INFO"] =~ /authed/
-        app.call(env)
-      else
-        [401, headers, "Not authed!"]
-      end
-    end
-  end
-
-  class Endpoint
-    def call(env)
-      [200, {}, "Hello World"]
-    end
-  end
-
-  class TestMiddleware < ActiveSupport::TestCase
-    def setup
-      @app = Rack::Builder.new do
-        use MetalTest::MetalMiddleware
-        run MetalTest::Endpoint.new
-      end.to_app
-    end
-
-    test "it can call the next app by using @app" do
-      env = Rack::MockRequest.env_for("/authed")
-      response = @app.call(env)
-
-      assert_equal ["Hello World"], response[2]
-    end
-
-    test "it can return a response using the normal AC::Metal techniques" do
-      env = Rack::MockRequest.env_for("/")
-      response = @app.call(env)
-
-      assert_equal ["Not authed!"], response[2]
-      assert_equal 401, response[0]
-    end
-  end
-end