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

src/heap/heap.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_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 146 matching lines @@
   V(Map, foreign_map, ForeignMap)                                              \
   V(Map, neander_map, NeanderMap)                                              \
   V(Map, external_map, ExternalMap)                                            \
   V(HeapNumber, nan_value, NanValue)                                           \
   V(HeapNumber, infinity_value, InfinityValue)                                 \
   V(HeapNumber, minus_zero_value, MinusZeroValue)                              \
   V(HeapNumber, minus_infinity_value, MinusInfinityValue)                      \
   V(JSObject, message_listeners, MessageListeners)                             \
   V(UnseededNumberDictionary, code_stubs, CodeStubs)                           \
   V(UnseededNumberDictionary, non_monomorphic_cache, NonMonomorphicCache)      \
-  V(PolymorphicCodeCache, polymorphic_code_cache, PolymorphicCodeCache)        \
   V(Code, js_entry_code, JsEntryCode)                                          \
   V(Code, js_construct_entry_code, JsConstructEntryCode)                       \
   V(FixedArray, natives_source_cache, NativesSourceCache)                      \
   V(FixedArray, experimental_natives_source_cache,                             \
     ExperimentalNativesSourceCache)                                            \
   V(FixedArray, extra_natives_source_cache, ExtraNativesSourceCache)           \
   V(FixedArray, experimental_extra_natives_source_cache,                       \
     ExperimentalExtraNativesSourceCache)                                       \
   V(Script, empty_script, EmptyScript)                                         \
   V(NameDictionary, intrinsic_function_names, IntrinsicFunctionNames)          \
@@ skipping 2473 matching lines @@
   friend class LargeObjectSpace;
   friend class NewSpace;
   friend class PagedSpace;
   DISALLOW_COPY_AND_ASSIGN(AllocationObserver);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_