[turbofan] Handle impossible types (Type::None()) in the backend.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 4d57144809da3eb16e2c5d2bca379c8777319c6d..21562393a4b48154ce5eef20e061063325a56bd4 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -2172,16 +2172,35 @@ Type* Typer::Visitor::TypeChangeInt32ToInt64(Node* node) {
   return Type::Internal();
 }
 
-
 Type* Typer::Visitor::TypeChangeUint32ToFloat64(Node* node) {
   return Type::Intersect(Type::Unsigned32(), Type::UntaggedFloat64(), zone());
 }
 
-
 Type* Typer::Visitor::TypeChangeUint32ToUint64(Node* node) {
   return Type::Internal();
 }
 
+Type* Typer::Visitor::TypeImpossibleToWord32(Node* node) {
+  return Type::None();
+}
+
+Type* Typer::Visitor::TypeImpossibleToWord64(Node* node) {
+  return Type::None();
+}
+
+Type* Typer::Visitor::TypeImpossibleToFloat32(Node* node) {
+  return Type::None();
+}
+
+Type* Typer::Visitor::TypeImpossibleToFloat64(Node* node) {
+  return Type::None();
+}
+
+Type* Typer::Visitor::TypeImpossibleToTagged(Node* node) {
+  return Type::None();
+}
+
+Type* Typer::Visitor::TypeImpossibleToBit(Node* node) { return Type::None(); }
 
 Type* Typer::Visitor::TypeTruncateFloat64ToFloat32(Node* node) {
   return Type::Intersect(Type::Number(), Type::UntaggedFloat32(), zone());
@@ -2192,7 +2211,6 @@ Type* Typer::Visitor::TypeTruncateFloat64ToWord32(Node* node) {
                          zone());
 }
 
-
 Type* Typer::Visitor::TypeTruncateInt64ToInt32(Node* node) {
   return Type::Intersect(Type::Signed32(), Type::UntaggedIntegral32(), zone());
 }