Remove most code related to serialized properties

Nearly completely implemented in terms of custom properties.
`_before_type_cast` now stores the raw serialized string consistently,
which removes the need to keep track of "state". The following is now
consistently true:

- `model.serialized == model.reload.serialized`
- A model can be dumped and loaded infinitely without changing
- A model can be saved and reloaded infinitely without changing

1 files changed, 0 insertions, 7 deletions

diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index b6fccc9b94..2e7b1d7206 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -14,7 +14,6 @@ module ActiveRecord
         finder_class = find_finder_class_for(record)
         table = finder_class.arel_table
         value = map_enum_attribute(finder_class, attribute, value)
-        value = deserialize_attribute(record, attribute, value)
 
         relation = build_relation(finder_class, table, attribute, value)
         relation = relation.and(table[finder_class.primary_key.to_sym].not_eq(record.id)) if record.persisted?
@@ -86,12 +85,6 @@ module ActiveRecord
         relation
       end
 
-      def deserialize_attribute(record, attribute, value)
-        coder = record.class.serialized_attributes[attribute.to_s]
-        value = coder.dump value if value && coder
-        value
-      end
-
       def map_enum_attribute(klass, attribute, value)
         mapping = klass.defined_enums[attribute.to_s]
         value = mapping[value] if value && mapping