[builtins] Properly optimize Object.prototype.isPrototypeOf.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 1b57bb2608d327841240e35ac2e59d36d0ffbf3c..33f4faf9f521175fc2f3086f3677319557bdf760 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -1274,6 +1274,11 @@ Type* Typer::Visitor::TypeJSHasProperty(Node* node) { return Type::Boolean(); }
 
 // JS instanceof operator.
 
+Type* Typer::Visitor::JSHasInPrototypeChainTyper(Type* lhs, Type* rhs,
+                                                 Typer* t) {
+  return Type::Boolean();
+}
+
 Type* Typer::Visitor::JSInstanceOfTyper(Type* lhs, Type* rhs, Typer* t) {
   return Type::Boolean();
 }
@@ -1515,6 +1520,7 @@ Type* Typer::Visitor::JSCallTyper(Type* fun, Typer* t) {
         case kObjectCreate:
           return Type::OtherObject();
         case kObjectHasOwnProperty:
+        case kObjectIsPrototypeOf:
           return Type::Boolean();
         case kObjectToString:
           return Type::String();