Improve the logic that detects non-autoloaded constants

If you require `nokogiri` from `app/models/user.rb`, dependencies.rb
does not mark `Nokogiri` as an autoloaded constant, as expected.
But the logic to detect these non-autoloaded constants is incomplete.
See the tests defined in the patch for some cases incorrectly handled.

activesupport/lib/active_support/dependencies.rb

@@ -103,6 +103,8 @@ class WatchStack
       # parent.rb then requires namespace/child.rb, the stack will look like
       # [[Object], [Namespace]].
 
+      attr_reader :watching
+
       def initialize
         @watching = []
         @stack = Hash.new { |h, k| h[k] = [] }
@@ -254,7 +256,9 @@ def require_dependency(file_name, message = "No such file to load -- %s.rb")
 
       def load_dependency(file)
         if Dependencies.load? && Dependencies.constant_watch_stack.watching?
-          Dependencies.new_constants_in(Object) { yield }
+          descs = Dependencies.constant_watch_stack.watching.flatten.uniq
+
+          Dependencies.new_constants_in(*descs) { yield }
         else
           yield
         end

activesupport/test/autoloading_fixtures/module_folder/nested_with_require.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+require "dependencies/module_folder/lib_class"
+
+module ModuleFolder
+  class NestedWithRequire
+  end
+end

activesupport/test/autoloading_fixtures/nested_with_require_parent.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class NestedWithRequireParent
+  ModuleFolder::NestedWithRequire
+end

activesupport/test/dependencies/module_folder/lib_class.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+ConstFromLib = 1
+
+module ModuleFolder
+  class LibClass
+  end
+end

activesupport/test/dependencies_test.rb

@@ -282,6 +282,32 @@ def test_module_with_nested_inline_class
     remove_constants(:ModuleFolder)
   end
 
+  def test_module_with_nested_class_requiring_lib_class
+    with_autoloading_fixtures do
+      ModuleFolder::NestedWithRequire
+
+      assert defined?(ModuleFolder::LibClass)
+      assert_not ActiveSupport::Dependencies.autoloaded_constants.include?("ModuleFolder::LibClass")
+      assert_not ActiveSupport::Dependencies.autoloaded_constants.include?("ConstFromLib")
+    end
+  ensure
+    remove_constants(:ModuleFolder)
+    remove_constants(:ConstFromLib)
+  end
+
+  def test_module_with_nested_class_and_parent_requiring_lib_class
+    with_autoloading_fixtures do
+      NestedWithRequireParent
+
+      assert defined?(ModuleFolder::LibClass)
+      assert_not ActiveSupport::Dependencies.autoloaded_constants.include?("ModuleFolder::LibClass")
+      assert_not ActiveSupport::Dependencies.autoloaded_constants.include?("ConstFromLib")
+    end
+  ensure
+    remove_constants(:ModuleFolder)
+    remove_constants(:ConstFromLib)
+  end
+
   def test_directories_may_manifest_as_nested_classes
     with_autoloading_fixtures do
       assert_kind_of Class, ClassFolder