[LookupIterator] Optimize the path that writes to fields.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index b141ac902adf9ebaea886d928abd561541132ede..78962bbe4cb4a5853d542e945644d6dd25b8534a 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2335,6 +2335,8 @@ class JSObject: public JSReceiver {
   inline void FastPropertyAtPut(FieldIndex index, Object* value);
   inline void RawFastPropertyAtPut(FieldIndex index, Object* value);
   inline void RawFastDoublePropertyAtPut(FieldIndex index, double value);
+  inline void WriteToField(int descriptor, PropertyDetails details,
+                           Object* value);
   inline void WriteToField(int descriptor, Object* value);
 
   // Access to in object properties.