Remove NonConcattingString.

actionpack/lib/action_view/base.rb

@@ -6,9 +6,6 @@ require 'active_support/ordered_options'
 require 'action_view/log_subscriber'
 
 module ActionView #:nodoc:
-  class NonConcattingString < ActiveSupport::SafeBuffer
-  end
-
   # = Action View Base
   #
   # Action View templates can be written in three ways. If the template file has a <tt>.erb</tt> (or <tt>.rhtml</tt>) extension then it uses a mixture of ERb

actionpack/lib/action_view/helpers/capture_helper.rb

@@ -38,7 +38,7 @@ module ActionView
         value = nil
         buffer = with_output_buffer { value = yield(*args) }
         if string = buffer.presence || value and string.is_a?(String)
-          NonConcattingString.new(string)
+          string
         end
       end
 

actionpack/test/template/capture_helper_test.rb

@@ -15,7 +15,6 @@ class CaptureHelperTest < ActionView::TestCase
     end
     assert_nil @av.output_buffer
     assert_equal 'foobar', string
-    assert_kind_of ActionView::NonConcattingString, string
   end
 
   def test_capture_captures_the_value_returned_by_the_block_if_the_temporary_buffer_is_blank
@@ -23,7 +22,6 @@ class CaptureHelperTest < ActionView::TestCase
       a + b
     end
     assert_equal 'foobar', string
-    assert_kind_of ActionView::NonConcattingString, string
   end
 
   def test_capture_returns_nil_if_the_returned_value_is_not_a_string