Inobject slack tracking is done on a per-closure basis instead of per-shared info basis.

src/builtins.h

 // Copyright 2011 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_BUILTINS_H_
 #define V8_BUILTINS_H_
 
 namespace v8 {
 namespace internal {
 
@@ skipping 49 matching lines @@
   V(HandleApiCallAsConstructor, NO_EXTRA_ARGUMENTS)                 \
                                                                     \
   V(StrictModePoisonPill, NO_EXTRA_ARGUMENTS)
 
 // Define list of builtins implemented in assembly.
 #define BUILTIN_LIST_A(V)                                               \
   V(ArgumentsAdaptorTrampoline,     BUILTIN, UNINITIALIZED,             \
                                     kNoExtraICState)                    \
   V(InOptimizationQueue,            BUILTIN, UNINITIALIZED,             \
                                     kNoExtraICState)                    \
-  V(JSConstructStubCountdown,       BUILTIN, UNINITIALIZED,             \
-                                    kNoExtraICState)                    \
   V(JSConstructStubGeneric,         BUILTIN, UNINITIALIZED,             \
                                     kNoExtraICState)                    \
   V(JSConstructStubApi,             BUILTIN, UNINITIALIZED,             \
                                     kNoExtraICState)                    \
   V(JSEntryTrampoline,              BUILTIN, UNINITIALIZED,             \
                                     kNoExtraICState)                    \
   V(JSConstructEntryTrampoline,     BUILTIN, UNINITIALIZED,             \
                                     kNoExtraICState)                    \
   V(CompileUnoptimized,             BUILTIN, UNINITIALIZED,             \
                                     kNoExtraICState)                    \
@@ skipping 250 matching lines @@
   static const char* const javascript_names_[id_count];
   static int const javascript_argc_[id_count];
 
   static void Generate_Adaptor(MacroAssembler* masm,
                                CFunctionId id,
                                BuiltinExtraArguments extra_args);
   static void Generate_CompileUnoptimized(MacroAssembler* masm);
   static void Generate_InOptimizationQueue(MacroAssembler* masm);
   static void Generate_CompileOptimized(MacroAssembler* masm);
   static void Generate_CompileOptimizedConcurrent(MacroAssembler* masm);
-  static void Generate_JSConstructStubCountdown(MacroAssembler* masm);
   static void Generate_JSConstructStubGeneric(MacroAssembler* masm);
   static void Generate_JSConstructStubApi(MacroAssembler* masm);
   static void Generate_JSEntryTrampoline(MacroAssembler* masm);
   static void Generate_JSConstructEntryTrampoline(MacroAssembler* masm);
   static void Generate_NotifyDeoptimized(MacroAssembler* masm);
   static void Generate_NotifySoftDeoptimized(MacroAssembler* masm);
   static void Generate_NotifyLazyDeoptimized(MacroAssembler* masm);
   static void Generate_NotifyStubFailure(MacroAssembler* masm);
   static void Generate_NotifyStubFailureSaveDoubles(MacroAssembler* masm);
   static void Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm);
@@ skipping 27 matching lines @@
 
   friend class BuiltinFunctionTable;
   friend class Isolate;
 
   DISALLOW_COPY_AND_ASSIGN(Builtins);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_BUILTINS_H_