Use weak cells in map checks in polymorphic ICs.

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 6168 matching lines @@
                                           CompilationInfo* info);
 
   static void AddDependentCode(Handle<Map> map,
                                DependentCode::DependencyGroup group,
                                Handle<Code> code);
   static void AddDependentIC(Handle<Map> map,
                              Handle<Code> stub);
 
   bool IsMapInArrayPrototypeChain();
 
+  static Handle<WeakCell> WeakCellForMap(Handle<Map> map);
+
   // Dispatched behavior.
   DECLARE_PRINTER(Map)
   DECLARE_VERIFIER(Map)
 
 #ifdef VERIFY_HEAP
   void DictionaryMapVerify();
   void VerifyOmittedMapChecks();
 #endif
 
   inline int visitor_id();
@@ skipping 4778 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_