[turbofan] Separate representation type operations from the semantic types.

src/hydrogen-types.cc

Index: src/hydrogen-types.cc
diff --git a/src/hydrogen-types.cc b/src/hydrogen-types.cc
index 4f5eabb2df82300acc1a02b87f5cbe9bbf05ef9d..3bac69bb569ae658c1448d955023591c611e07a5 100644
--- a/src/hydrogen-types.cc
+++ b/src/hydrogen-types.cc
@@ -15,7 +15,7 @@ namespace internal {
 template <class T>
 HType HType::FromType(typename T::TypeHandle type) {
   if (T::Any()->Is(type)) return HType::Any();
-  if (type->Is(T::None())) return HType::None();
+  if (!type->IsInhabited()) return HType::None();
   if (type->Is(T::SignedSmall())) return HType::Smi();
   if (type->Is(T::Number())) return HType::TaggedNumber();
   if (type->Is(T::Null())) return HType::Null();