Retain maps embedded in optimized code for several garbage collections.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 943a30fc7abb03313e082a357da4014e545b0e54..9dd8ed4ae5fc1bd2032f8f30d26054d97eb6e3de 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -183,6 +183,7 @@ namespace internal {
   V(FixedArray, microtask_queue, MicrotaskQueue)                               \
   V(FixedArray, keyed_load_dummy_vector, KeyedLoadDummyVector)                 \
   V(FixedArray, detached_contexts, DetachedContexts)                           \
+  V(ArrayList, retained_maps, RetainedMaps)                                    \
   V(WeakHashTable, weak_object_to_code_table, WeakObjectToCodeTable)
 
 // Entries in this list are limited to Smis and are not visited during GC.
@@ -1439,6 +1440,8 @@ class Heap {
 
   DependentCode* LookupWeakObjectToCodeDependency(Handle<HeapObject> obj);
 
+  void AddRetainedMap(Handle<Map> map);
+
   static void FatalProcessOutOfMemory(const char* location,
                                       bool take_snapshot = false);