Improve memory usage of receiver type feedback.

src/zone.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 178 matching lines @@
       : List<T, ZoneListAllocationPolicy>(capacity) { }
 
   // Construct a new ZoneList by copying the elements of the given ZoneList.
   explicit ZoneList(const ZoneList<T>& other)
       : List<T, ZoneListAllocationPolicy>(other.length()) {
     AddAll(other);
   }
 };
 
 
-// Introduce a convenience type for zone lists of map handles.
-typedef ZoneList<Handle<Map> > ZoneMapList;
-
-
 // ZoneScopes keep track of the current parsing and compilation
 // nesting and cleans up generated ASTs in the Zone when exiting the
 // outer-most scope.
 class ZoneScope BASE_EMBEDDED {
  public:
   INLINE(ZoneScope(Isolate* isolate, ZoneScopeMode mode));
 
   virtual ~ZoneScope();
 
   inline bool ShouldDeleteOnExit();
@@ skipping 20 matching lines @@
  public:
   ZoneSplayTree()
       : SplayTree<Config, ZoneListAllocationPolicy>() {}
   ~ZoneSplayTree();
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ZONE_H_