Promoting elements transitions to their own field.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index c68befd15ae14b72ad439899d17e310e0cdc1f89..2c2b208f02598926d0a062e93163688f2947b220 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -2092,7 +2092,7 @@ class HCheckMaps: public HTemplateInstruction<2> {
     while (CanTransitionToMoreGeneralFastElementsKind(kind, packed)) {
       kind = GetNextMoreGeneralFastElementsKind(kind, packed);
       Map* transitioned_map =
-          map->LookupElementsTransitionMap(kind, NULL);
+          map->LookupElementsTransitionMap(kind);
       if (transitioned_map) {
         map_set->Add(Handle<Map>(transitioned_map));
       }