Fix to allocation stub invalidation: we cannot just remove it as it will be collected even though c…

runtime/vm/object.h

Index: runtime/vm/object.h
===================================================================
--- runtime/vm/object.h	(revision 40205)
+++ runtime/vm/object.h	(working copy)
@@ -1270,6 +1270,10 @@
   void set_canonical_types(const Object& value) const;
   RawObject* canonical_types() const;
 
+  RawCode* spare_allocation_stub() const {
+    return raw_ptr()->spare_allocation_stub_;
+  }
+
   RawArray* invocation_dispatcher_cache() const;
   void set_invocation_dispatcher_cache(const Array& cache) const;
   RawFunction* CreateInvocationDispatcher(const String& target_name,