Use a dictionary-mode code cache on the map rather than a dual system.

src/types.cc

Index: src/types.cc
diff --git a/src/types.cc b/src/types.cc
index 49c941816eb07aa72d68efe84914b411c988deff..928f3bdbe56f3a9a3c8f734f8ca5cd19fbc73887 100644
--- a/src/types.cc
+++ b/src/types.cc
@@ -266,8 +266,6 @@ Type::bitset BitsetType::Lub(i::Map* map) {
     case SIGNATURE_INFO_TYPE:
     case TYPE_SWITCH_INFO_TYPE:
     case ALLOCATION_MEMENTO_TYPE:
-    case CODE_CACHE_TYPE:
-    case POLYMORPHIC_CODE_CACHE_TYPE:
     case TYPE_FEEDBACK_INFO_TYPE:
     case ALIASED_ARGUMENTS_ENTRY_TYPE:
     case BOX_TYPE: