feat(library/type_context): improve precision
feat(library/type_context): improve precision

Kha/lean,fpvandoorn/lean,leanprover/lean,rlewis1988/lean,rlewis1988/lean,leanprover/lean,leanprover-community/lean,dselsam/lean,fpvandoorn/lean,leanprover-community/lean,johoelzl/lean,digama0/lean,digama0/lean,avigad/lean,johoelzl/lean,dselsam/lean,fgdorais/lean,leodemoura/lean,fpvandoorn/lean,leanprover/lean,Kha/lean,leanprover/lean,fpvandoorn/lean,leanprover-community/lean,avigad/lean,leanprover-community/lean,leodemoura/lean,digama0/lean,Kha/lean,rlewis1988/lean,digama0/lean,fpvandoorn/lean,Kha/lean,digama0/lean,leodemoura/lean,johoelzl/lean,rlewis1988/lean,johoelzl/lean,dselsam/lean,leanprover-community/lean,dselsam/lean,leanprover/lean,avigad/lean,rlewis1988/lean,dselsam/lean,rlewis1988/lean,avigad/lean,fgdorais/lean,leanprover-community/lean,fgdorais/lean,fgdorais/lean,fgdorais/lean,leanprover/lean,leodemoura/lean,avigad/lean,johoelzl/lean,avigad/lean,leodemoura/lean,digama0/lean,Kha/lean,leodemoura/lean,johoelzl/lean,dselsam/lean,fgdorais/lean,fpvandoorn/lean,Kha/lean