Revert of [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 e7638019a398cf7821ce57ef5054e1415c6cdc1d..9679513219d666f64a9d2b7ebf5be1371c68acdb 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -57,8 +57,10 @@
   unsigned32ish_ = Type::Union(Type::Unsigned32(), truncating_to_zero, zone);
   falsish_ = Type::Union(
       Type::Undetectable(),
-      Type::Union(Type::Union(singleton_false_, cache_.kZeroish, zone),
-                  singleton_the_hole_, zone),
+      Type::Union(
+          Type::Union(Type::Union(singleton_false_, cache_.kZeroish, zone),
+                      Type::NullOrUndefined(), zone),
+          singleton_the_hole_, zone),
       zone);
   truish_ = Type::Union(
       singleton_true_,
@@ -242,7 +244,6 @@
   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*);
@@ -468,9 +469,7 @@
   // 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::OtherUndetectable())) {
-    return Type::DetectableReceiver();
-  }
+  if (!type->Maybe(Type::Undetectable())) return Type::DetectableReceiver();
   return Type::Receiver();
 }
 
@@ -530,13 +529,6 @@
 Type* Typer::Visitor::ObjectIsSmi(Type* type, Typer* t) {
   if (type->Is(Type::TaggedSigned())) return t->singleton_true_;
   if (type->Is(Type::TaggedPointer())) return t->singleton_false_;
-  return Type::Boolean();
-}
-
-
-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();
 }
 
@@ -1179,7 +1171,7 @@
     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::OtherUndetectable(),
+  } else if (type->Is(Type::Union(Type::Undefined(), Type::Undetectable(),
                                   t->zone()))) {
     return Type::Constant(f->undefined_string(), t->zone());
   } else if (type->Is(Type::Null())) {
@@ -1933,11 +1925,6 @@
 }
 
 
-Type* Typer::Visitor::TypeObjectIsUndetectable(Node* node) {
-  return TypeUnaryOp(node, ObjectIsUndetectable);
-}
-
-
 // Machine operators.
 
 Type* Typer::Visitor::TypeLoad(Node* node) { return Type::Any(); }