[turbofan] Optimize typeof operator without storing strings in Type

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 0d2bde2db809ef416b9f092d24e2b5fefbbbb1c2..fe6507fb162e07cb8ed71dfcf01ad2275037a6ae 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -290,7 +290,6 @@ class Typer::Visitor : public Reducer {
   JS_SIMPLE_BINOP_LIST(DECLARE_METHOD)
 #undef DECLARE_METHOD
 
-  static Type* JSTypeOfTyper(Type*, Typer*);
   static Type* JSCallFunctionTyper(Type*, Typer*);
 
   static Type* ReferenceEqualTyper(Type*, Type*, Typer*);
@@ -1013,36 +1012,8 @@ Type* Typer::Visitor::JSModulusTyper(Type* lhs, Type* rhs, Typer* t) {
 // JS unary operators.
 
 
-Type* Typer::Visitor::JSTypeOfTyper(Type* type, Typer* t) {
-  Factory* const f = t->isolate()->factory();
-  if (type->Is(Type::Boolean())) {
-    return Type::HeapConstant(f->boolean_string(), t->zone());
-  } else if (type->Is(Type::Number())) {
-    return Type::HeapConstant(f->number_string(), t->zone());
-  } else if (type->Is(Type::String())) {
-    return Type::HeapConstant(f->string_string(), t->zone());
-  } else if (type->Is(Type::Symbol())) {
-    return Type::HeapConstant(f->symbol_string(), t->zone());
-  } else if (type->Is(Type::Union(Type::Undefined(), Type::OtherUndetectable(),
-                                  t->zone()))) {
-    return Type::HeapConstant(f->undefined_string(), t->zone());
-  } else if (type->Is(Type::Null())) {
-    return Type::HeapConstant(f->object_string(), t->zone());
-  } else if (type->Is(Type::Function())) {
-    return Type::HeapConstant(f->function_string(), t->zone());
-  } else if (type->IsHeapConstant()) {
-    return Type::HeapConstant(
-        Object::TypeOf(t->isolate(), type->AsHeapConstant()->Value()),
-        t->zone());
-  } else if (type->IsOtherNumberConstant()) {
-    return Type::HeapConstant(f->number_string(), t->zone());
-  }
-  return Type::InternalizedString();
-}
-
-
 Type* Typer::Visitor::TypeJSTypeOf(Node* node) {
-  return TypeUnaryOp(node, JSTypeOfTyper);
+  return Type::InternalizedString();
 }