Remove special case filtering for Procs.

I'm writing this patch for two purposes:

1. I want to reduce the number of times `object_id` is called.  Calling
   `object_id` can have negative impacts on performance in Ruby 2.7+, so
   it would be nice to stop calling it.

2. I'm not sure why we're treating lambdas specially here.  It looks
   like we wanted to prevent people from skipping callbacks that were
   defined with a lambda, but I think that is silly.  If the user has a
   reference to a lambda, and they want to skip it, we should let them.

I think this cleans up some code, helps with performance, and is a more
intuitive interface.

actionpack/test/controller/filters_test.rb

@@ -12,7 +12,7 @@ class << self
 
     def before_actions
       filters = _process_action_callbacks.select { |c| c.kind == :before }
-      filters.map!(&:raw_filter)
+      filters.map!(&:filter)
     end
   end
 end

activesupport/lib/active_support/callbacks.rb

@@ -289,21 +289,17 @@ def self.build(chain, filter, kind, options)
         end
 
         attr_accessor :kind, :name
-        attr_reader :chain_config
+        attr_reader :chain_config, :filter
 
         def initialize(name, filter, kind, options, chain_config)
           @chain_config = chain_config
           @name    = name
           @kind    = kind
           @filter  = filter
-          @key     = compute_identifier filter
           @if      = check_conditionals(options[:if])
           @unless  = check_conditionals(options[:unless])
         end
 
-        def filter; @key; end
-        def raw_filter; @filter; end
-
         def merge_conditional_options(chain, if_option:, unless_option:)
           options = {
             if: @if.dup,
@@ -367,15 +363,6 @@ def check_conditionals(conditionals)
             conditionals.freeze
           end
 
-          def compute_identifier(filter)
-            case filter
-            when ::Proc
-              filter.object_id
-            else
-              filter
-            end
-          end
-
           def conditions_lambdas
             @if.map { |c| CallTemplate.build(c, self).make_lambda } +
               @unless.map { |c| CallTemplate.build(c, self).inverted_lambda }

activesupport/test/callbacks_test.rb

@@ -1129,15 +1129,6 @@ def test_skip_class # removes one at a time
       }
     end
 
-    def test_skip_lambda # raises error
-      calls = []
-      callback = ->(o) { calls << o }
-      klass = build_class(callback)
-      assert_raises(ArgumentError) { klass.skip callback }
-      klass.new.run
-      assert_equal 10, calls.length
-    end
-
     def test_skip_symbol # removes all
       calls = []
       klass = build_class(:bar)

activesupport/test/test_case_test.rb

@@ -325,9 +325,9 @@ class SetupAndTeardownTest < ActiveSupport::TestCase
   teardown :foo, :sentinel
 
   def test_inherited_setup_callbacks
-    assert_equal [:reset_callback_record, :foo], self.class._setup_callbacks.map(&:raw_filter)
+    assert_equal [:reset_callback_record, :foo], self.class._setup_callbacks.map(&:filter)
     assert_equal [:foo], @called_back
-    assert_equal [:foo, :sentinel], self.class._teardown_callbacks.map(&:raw_filter)
+    assert_equal [:foo, :sentinel], self.class._teardown_callbacks.map(&:filter)
   end
 
   def setup
@@ -355,9 +355,9 @@ class SubclassSetupAndTeardownTest < SetupAndTeardownTest
   teardown :bar
 
   def test_inherited_setup_callbacks
-    assert_equal [:reset_callback_record, :foo, :bar], self.class._setup_callbacks.map(&:raw_filter)
+    assert_equal [:reset_callback_record, :foo, :bar], self.class._setup_callbacks.map(&:filter)
     assert_equal [:foo, :bar], @called_back
-    assert_equal [:foo, :sentinel, :bar], self.class._teardown_callbacks.map(&:raw_filter)
+    assert_equal [:foo, :sentinel, :bar], self.class._teardown_callbacks.map(&:filter)
   end
 
   private