Refactor SharedFunctionInfo::IsBuiltin.

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 f3502568d6dde6107133f3e47633a02efdca44e6..fc1311c643c99597a336039cf5fe5fd170d1a266 100644
--- a/src/heap/objects-visiting-inl.h
+++ b/src/heap/objects-visiting-inl.h
@@ -600,8 +600,8 @@ bool StaticMarkingVisitor<StaticVisitor>::IsFlushable(
     return false;
   }
 
-  // The function must not be a builtin.
-  if (shared_info->IsBuiltin()) {
+  // The function must be user code.
+  if (!shared_info->IsUserJavaScript()) {
     return false;
   }