Reload length of retained_maps array after GC.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 3f652531ecd77f21bb3b7942e8d530f92d66b56a..2ac5146c46d0cf06c6f00f2bbea878a0015db66b 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -5613,7 +5613,8 @@ void Heap::AddRetainedMap(Handle<Map> map) {
   Handle<WeakCell> cell = Map::WeakCellForMap(map);
   Handle<ArrayList> array(retained_maps(), isolate());
   array = ArrayList::Add(
-      array, cell, handle(Smi::FromInt(FLAG_retain_maps_for_n_gc), isolate()));
+      array, cell, handle(Smi::FromInt(FLAG_retain_maps_for_n_gc), isolate()),
+      ArrayList::kReloadLengthAfterAllocation);
   if (*array != retained_maps()) {
     set_retained_maps(*array);
   }