Micro-optimize lookupiterator: faster path for fast-mode objects

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 9f535ca64d4cd0475e3e74db6c75ad90fb337757..4b143c8b8b63b6996b99dd84b9e4c6e3fc834ad7 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -1028,10 +1028,7 @@ bool Object::IsJSGlobalProxy() const {
 
 bool Object::IsGlobalObject() const {
   if (!IsHeapObject()) return false;
-
-  InstanceType type = HeapObject::cast(this)->map()->instance_type();
-  return type == JS_GLOBAL_OBJECT_TYPE ||
-         type == JS_BUILTINS_OBJECT_TYPE;
+  return HeapObject::cast(this)->map()->IsGlobalObjectMap();
 }