Fix non-standard element handling

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 50772bafc201ff56afd53d3eeae033153f5d4173..f338f762e617841d0f9c3c7005be348941dee9aa 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2102,6 +2102,8 @@ class JSObject: public JSReceiver {
   static Handle<SeededNumberDictionary> NormalizeElements(
       Handle<JSObject> object);
 
+  void RequireSlowElements(SeededNumberDictionary* dictionary);
+
   // Transform slow named properties to fast variants.
   static void MigrateSlowToFast(Handle<JSObject> object,
                                 int unused_property_fields, const char* reason);