Fix building of closure type arguments (fixes #25543).

runtime/vm/flow_graph_builder.h

Index: runtime/vm/flow_graph_builder.h
diff --git a/runtime/vm/flow_graph_builder.h b/runtime/vm/flow_graph_builder.h
index 4025fe8ed6e7e72b761e9a3d2c66bfe60655b776..2c2d14d713b3d1746b7fd32f7852ddfe686c98e7 100644
--- a/runtime/vm/flow_graph_builder.h
+++ b/runtime/vm/flow_graph_builder.h
@@ -343,7 +343,7 @@ class EffectGraphVisitor : public AstNodeVisitor {
       PushArgumentInstr** push_instantiator_type_arguments);
   void BuildTypecheckArguments(intptr_t token_pos,
                                Value** instantiator_type_arguments);
-  Value* BuildInstantiator(intptr_t token_pos, const Class& instantiator_class);
+  Value* BuildInstantiator(intptr_t token_pos);
   Value* BuildInstantiatorTypeArguments(intptr_t token_pos,
                                         const Class& instantiator_class,
                                         Value* instantiator);