[builtins] Add support for JS builtins written in TurboFan.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 619fb778ecd637d7f1a960460644c6550d7353b6..7c1bdac4d58a8553025bbe4ae9b0a9050cef6300 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -4925,14 +4925,10 @@ void Code::set_profiler_ticks(int ticks) {
   }
 }
 
-
-int Code::builtin_index() {
-  return READ_INT32_FIELD(this, kKindSpecificFlags1Offset);
-}
-
+int Code::builtin_index() { return READ_INT_FIELD(this, kBuiltinIndexOffset); }
 
 void Code::set_builtin_index(int index) {
-  WRITE_INT32_FIELD(this, kKindSpecificFlags1Offset, index);
+  WRITE_INT_FIELD(this, kBuiltinIndexOffset, index);
 }