[heap] Use safer predicate for API functions.

src/heap/objects-visiting-inl.h

Index: src/heap/objects-visiting-inl.h
diff --git a/src/heap/objects-visiting-inl.h b/src/heap/objects-visiting-inl.h
index b714335132c168449d155871410f79680bd6cd6f..d77a4a1d2a05137ee754eeb327b7bfcb1cd93048 100644
--- a/src/heap/objects-visiting-inl.h
+++ b/src/heap/objects-visiting-inl.h
@@ -625,8 +625,7 @@ bool StaticMarkingVisitor<StaticVisitor>::IsFlushable(
   }
 
   // We never flush code for API functions.
-  Object* function_data = shared_info->function_data();
-  if (function_data->IsFunctionTemplateInfo()) {
+  if (shared_info->IsApiFunction()) {
     return false;
   }