Add AnyArityFunType to subtyping and vars elimination

Summary: Somehow missed this when adding support for `AnyArityFunType`.

Reviewed By: ilya-klyuchnikov, ruippeixotog

Differential Revision: D60777722

fbshipit-source-id: f22af0791038124e283d1f6a91c3fed33d7eabd4

Author: VLanvin

eqwalizer/src/main/scala/com/whatsapp/eqwalizer/tc/Subtype.scala

@@ -159,6 +159,8 @@ class Subtype(pipelineContext: PipelineContext) {
         subTypePol(resTy1, resTy2, seen)
       case (AnyArityFunType(resTy1), FunType(_, _, resTy2)) =>
         subTypePol(resTy1, resTy2, seen)
+      case (AnyArityFunType(resTy1), AnyArityFunType(resTy2)) =>
+        subTypePol(resTy1, resTy2, seen)
       case (TupleType(tys1), TupleType(tys2)) if tys1.size == tys2.size =>
         tys1.lazyZip(tys2).forall(subTypePol(_, _, seen))
       case (NilType, ListType(_)) =>

eqwalizer/src/main/scala/com/whatsapp/eqwalizer/tc/generics/ElimTypeVars.scala

@@ -28,6 +28,8 @@ object ElimTypeVars {
       case FunType(forall, args, resType) =>
         val args1 = args.map(elimTypeVars(_, switchMode(mode), vars))
         FunType(forall, args1, elim(resType))
+      case AnyArityFunType(resType) =>
+        AnyArityFunType(elim(resType))
       case TupleType(params) =>
         TupleType(params.map(elim))
       case ListType(elemT) =>