message: Fix annotation stratification
diff: % Variables
  % Annotated terms
  - is_type Context (core.ann SourceElem SourceType) TargetElem :-
  - is_type Context SourceType TargetType,
  - context.eval Context TargetType TargetType',
  - check_type Context SourceElem TargetType' TargetElem.
  + synth_type Context (core.ann SourceElem SourceType) (kind TargetType')
  + (type' (stratified.ann TargetElem TargetType))
  + :-
  + is_type Context SourceType (kind TargetType),
  + context.eval Context (kind TargetType) (kind TargetType'),
  + check_type Context SourceElem (kind TargetType') (type' TargetElem).
  + synth_type Context (core.ann SourceElem SourceType) (type' TargetType')
  + (term (stratified.ann TargetElem TargetType))
  + :-
  + is_type Context SourceType (type' TargetType),
  + context.eval Context (type' TargetType) (type' TargetType'),
  + check_type Context SourceElem (type' TargetType') (term TargetElem).
  % Universes
  is_type Context core.type_type (kind stratified.type_type).
  