[compiler] Drop the CompareNilIC.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 5270be010cf6c476c318aa47b8d1f1c31038730b..6778c8d3b3a8e4e8207f9cf65013663447f9f9bd 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -57,10 +57,8 @@ Typer::Typer(Isolate* isolate, Graph* graph, Flags flags,
   unsigned32ish_ = Type::Union(Type::Unsigned32(), truncating_to_zero, zone);
   falsish_ = Type::Union(
       Type::Undetectable(),
-      Type::Union(
-          Type::Union(Type::Union(singleton_false_, cache_.kZeroish, zone),
-                      Type::NullOrUndefined(), zone),
-          singleton_the_hole_, zone),
+      Type::Union(Type::Union(singleton_false_, cache_.kZeroish, zone),
+                  singleton_the_hole_, zone),
       zone);
   truish_ = Type::Union(
       singleton_true_,
@@ -248,6 +246,7 @@ class Typer::Visitor : public Reducer {
   static Type* ObjectIsNumber(Type*, Typer*);
   static Type* ObjectIsReceiver(Type*, Typer*);
   static Type* ObjectIsSmi(Type*, Typer*);
+  static Type* ObjectIsUndetectable(Type*, Typer*);
 
   static Type* JSAddRanger(RangeType*, RangeType*, Typer*);
   static Type* JSSubtractRanger(RangeType*, RangeType*, Typer*);
@@ -473,7 +472,9 @@ Type* Typer::Visitor::ToObject(Type* type, Typer* t) {
   // ES6 section 7.1.13 ToObject ( argument )
   if (type->Is(Type::Receiver())) return type;
   if (type->Is(Type::Primitive())) return Type::OtherObject();
-  if (!type->Maybe(Type::Undetectable())) return Type::DetectableReceiver();
+  if (!type->Maybe(Type::OtherUndetectable())) {
+    return Type::DetectableReceiver();
+  }
   return Type::Receiver();
 }
 
@@ -537,6 +538,13 @@ Type* Typer::Visitor::ObjectIsSmi(Type* type, Typer* t) {
 }
 
 
+Type* Typer::Visitor::ObjectIsUndetectable(Type* type, Typer* t) {
+  if (type->Is(Type::Undetectable())) return t->singleton_true_;
+  if (!type->Maybe(Type::Undetectable())) return t->singleton_false_;
+  return Type::Boolean();
+}
+
+
 // -----------------------------------------------------------------------------
 
 
@@ -1175,7 +1183,7 @@ Type* Typer::Visitor::JSTypeOfTyper(Type* type, Typer* t) {
     return Type::Constant(f->string_string(), t->zone());
   } else if (type->Is(Type::Symbol())) {
     return Type::Constant(f->symbol_string(), t->zone());
-  } else if (type->Is(Type::Union(Type::Undefined(), Type::Undetectable(),
+  } else if (type->Is(Type::Union(Type::Undefined(), Type::OtherUndetectable(),
                                   t->zone()))) {
     return Type::Constant(f->undefined_string(), t->zone());
   } else if (type->Is(Type::Null())) {
@@ -1926,6 +1934,11 @@ Type* Typer::Visitor::TypeObjectIsSmi(Node* node) {
 }
 
 
+Type* Typer::Visitor::TypeObjectIsUndetectable(Node* node) {
+  return TypeUnaryOp(node, ObjectIsUndetectable);
+}
+
+
 // Machine operators.
 
 Type* Typer::Visitor::TypeLoad(Node* node) { return Type::Any(); }