ActionPack Proc.new without a block

This commit fixes cases that use pre Ruby
[r66772](https://bugs.ruby-lang.org/projects/ruby-trunk/repository/trunk/revisions/66772)
syntax that are not tickled by the test suite.

2 files changed, 4 insertions, 4 deletions

diff --git a/actionpack/lib/action_controller/metal.rb b/actionpack/lib/action_controller/metal.rb
index f875aa5e6b..b9088e6d86 100644
--- a/actionpack/lib/action_controller/metal.rb
+++ b/actionpack/lib/action_controller/metal.rb
@@ -26,10 +26,10 @@ module ActionController
       end
     end
 
-    def build(action, app = Proc.new)
+    def build(action, app = nil, &block)
       action = action.to_s
 
-      middlewares.reverse.inject(app) do |a, middleware|
+      middlewares.reverse.inject(app || block) do |a, middleware|
         middleware.valid?(action) ? middleware.build(a) : a
       end
     end
diff --git a/actionpack/lib/action_dispatch/middleware/stack.rb b/actionpack/lib/action_dispatch/middleware/stack.rb
index b82f8aa3a3..7a2fcd6db7 100644
--- a/actionpack/lib/action_dispatch/middleware/stack.rb
+++ b/actionpack/lib/action_dispatch/middleware/stack.rb
@@ -97,8 +97,8 @@ module ActionDispatch
       middlewares.push(build_middleware(klass, args, block))
     end
 
-    def build(app = Proc.new)
-      middlewares.freeze.reverse.inject(app) { |a, e| e.build(a) }
+    def build(app = nil, &block)
+      middlewares.freeze.reverse.inject(app || block) { |a, e| e.build(a) }
     end
 
     private