Do not validate Function fields even with setter

Their values should be already validated by the underlying storage and also
the domain validation requires to have a searcher.

issue7507
review48471002

CHANGELOG

@@ -1,3 +1,4 @@
+* Do not validate Function fields even with setter
 * Simplify the creation of dependencies graph
 * Make depends on methods generic to any method
 * Add width/height attribute to notebook

trytond/model/modelstorage.py

@@ -980,8 +980,7 @@ class ModelStorage(Model):
                         and not (depends & field_names)
                         and not (depends & function_fields)):
                     continue
-                if isinstance(field, fields.Function) and \
-                        not field.setter:
+                if isinstance(field, fields.Function):
                     continue
 
                 validate_domain(field)