normalizer: make prims_to_fstar_range a WEAK step
normalizer: make prims_to_fstar_range a WEAK step

this was messing up typing, we cannot just do this on open contexts,
particularly for SMT queries

FStarLang/FStar,A-Manning/FStar,FStarLang/FStar,A-Manning/FStar,FStarLang/FStar,A-Manning/FStar