Remove valid_type? method

It was supposed to be removed by the preceding two reversions but I did
them in the wrong order.

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -326,10 +326,6 @@ def translate_exception(exception, message)
         # override in derived class
         ActiveRecord::StatementInvalid.new(message)
       end
-
-      def valid_types?(type)
-        true
-      end
     end
   end
 end

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -747,10 +747,6 @@ def configure_connection
         # ...and send them all in one query
         execute("SET #{encoding} #{variable_assignments}", :skip_logging)
       end
-
-      def valid_type?(type)
-        !native_database_types[type].nil?
-      end  
     end
   end
 end

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -887,10 +887,6 @@ def extract_table_ref_from_insert_sql(sql)
         def table_definition
           TableDefinition.new(self)
         end
-
-        def valid_type?(type)
-          !native_database_types[type].nil?
-        end
     end
   end
 end

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -602,11 +602,6 @@ def translate_exception(exception, message)
             super
           end
         end
-
-        def valid_type?(type)
-          true
-        end
-
     end
   end
 end