Make ClassFinalizer indifferent on whether we are generating a snapshot or not.

runtime/vm/flow_graph_builder.cc

Index: runtime/vm/flow_graph_builder.cc
===================================================================
--- runtime/vm/flow_graph_builder.cc	(revision 11113)
+++ runtime/vm/flow_graph_builder.cc	(working copy)
@@ -1585,7 +1585,8 @@
     // Type is temporary. Only its type arguments are preserved.
     Type& type = Type::Handle(
         Type::New(instantiator_class, type_arguments, token_pos, Heap::kNew));
-    type ^= ClassFinalizer::FinalizeType(
+    ClassFinalizer class_finalizer(ClassFinalizer::kNotGeneratingSnapshot);
+    type ^= class_finalizer.FinalizeType(
         instantiator_class, type, ClassFinalizer::kFinalize);
     ASSERT(!type.IsMalformed());
     type_arguments = type.arguments();