Remove the SQLite3 Binary subclass

As far as I can tell, the original reason that this behavior was added
has been sufficiently resolved elsewhere, as we no longer remove the
encoding of strings coming out of the database.

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -41,15 +41,6 @@ def sqlite3_connection(config)
   end
 
   module ConnectionAdapters #:nodoc:
-    class SQLite3Binary < Type::Binary # :nodoc:
-      def cast_value(value)
-        if value.encoding != Encoding::ASCII_8BIT
-          value = value.force_encoding(Encoding::ASCII_8BIT)
-        end
-        value
-      end
-    end
-
     # The SQLite3 adapter works SQLite 3.6.16 or newer
     # with the sqlite3-ruby drivers (available as gem from https://rubygems.org/gems/sqlite3).
     #
@@ -240,10 +231,6 @@ def _type_cast(value) # :nodoc:
         end
       end
 
-      def type_classes_with_standard_constructor
-        super.merge(binary: SQLite3Binary)
-      end
-
       def quote_string(s) #:nodoc:
         @connection.class.quote(s)
       end
@@ -493,11 +480,6 @@ def rename_column(table_name, column_name, new_column_name) #:nodoc:
 
       protected
 
-        def initialize_type_map(m)
-          super
-          m.register_type(/binary/i, SQLite3Binary.new)
-        end
-
         def table_structure(table_name)
           structure = exec_query("PRAGMA table_info(#{quote_table_name(table_name)})", 'SCHEMA').to_hash
           raise(ActiveRecord::StatementInvalid, "Could not find table '#{table_name}'") if structure.empty?

activerecord/test/cases/types_test.rb

@@ -108,16 +108,6 @@ def test_type_equality
         assert_not_equal Type::Value.new(precision: 1), Type::Value.new(precision: 2)
       end
 
-      if current_adapter?(:SQLite3Adapter)
-        def test_binary_encoding
-          type = SQLite3Binary.new
-          utf8_string = "a string".encode(Encoding::UTF_8)
-          type_cast = type.type_cast_from_user(utf8_string)
-
-          assert_equal Encoding::ASCII_8BIT, type_cast.encoding
-        end
-      end
-
       def test_attributes_which_are_invalid_for_database_can_still_be_reassigned
         type_which_cannot_go_to_the_database = Type::Value.new
         def type_which_cannot_go_to_the_database.type_cast_for_database(*)