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

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 778bcb33d2e01867ea0bcb071c91b3f85b7e27bf..319e6a82dc2a401a17988e4775212b8335062f4e 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -4072,6 +4072,19 @@ bool Map::is_extensible() {
 }
 
 
+void Map::set_attached_to_shared_function_info(bool value) {
+  if (value) {
+    set_bit_field2(bit_field2() | (1 << kAttachedToSharedFunctionInfo));
+  } else {
+    set_bit_field2(bit_field2() & ~(1 << kAttachedToSharedFunctionInfo));
+  }
+}
+
+bool Map::attached_to_shared_function_info() {
+  return ((1 << kAttachedToSharedFunctionInfo) & bit_field2()) != 0;
+}
+
+
 void Map::set_is_shared(bool value) {
   set_bit_field3(IsShared::update(bit_field3(), value));
 }
@@ -4138,26 +4151,6 @@ bool Map::is_migration_target() {
 }
 
 
-void Map::set_done_inobject_slack_tracking(bool value) {
-  set_bit_field3(DoneInobjectSlackTracking::update(bit_field3(), value));
-}
-
-
-bool Map::done_inobject_slack_tracking() {
-  return DoneInobjectSlackTracking::decode(bit_field3());
-}
-
-
-void Map::set_construction_count(int value) {
-  set_bit_field3(ConstructionCount::update(bit_field3(), value));
-}
-
-
-int Map::construction_count() {
-  return ConstructionCount::decode(bit_field3());
-}
-
-
 void Map::freeze() {
   set_bit_field3(IsFrozen::update(bit_field3(), true));
 }
@@ -5058,6 +5051,7 @@ ACCESSORS(SharedFunctionInfo, optimized_code_map, Object,
 ACCESSORS(SharedFunctionInfo, construct_stub, Code, kConstructStubOffset)
 ACCESSORS(SharedFunctionInfo, feedback_vector, FixedArray,
           kFeedbackVectorOffset)
+ACCESSORS(SharedFunctionInfo, initial_map, Object, kInitialMapOffset)
 ACCESSORS(SharedFunctionInfo, instance_class_name, Object,
           kInstanceClassNameOffset)
 ACCESSORS(SharedFunctionInfo, function_data, Object, kFunctionDataOffset)
@@ -5182,6 +5176,28 @@ PSEUDO_SMI_ACCESSORS_HI(SharedFunctionInfo,
 #endif
 
 
+int SharedFunctionInfo::construction_count() {
+  return READ_BYTE_FIELD(this, kConstructionCountOffset);
+}
+
+
+void SharedFunctionInfo::set_construction_count(int value) {
+  ASSERT(0 <= value && value < 256);
+  WRITE_BYTE_FIELD(this, kConstructionCountOffset, static_cast<byte>(value));
+}
+
+
+BOOL_ACCESSORS(SharedFunctionInfo,
+               compiler_hints,
+               live_objects_may_exist,
+               kLiveObjectsMayExist)
+
+
+bool SharedFunctionInfo::IsInobjectSlackTrackingInProgress() {
+  return initial_map() != GetHeap()->undefined_value();
+}
+
+
 BOOL_GETTER(SharedFunctionInfo,
             compiler_hints,
             optimization_disabled,
@@ -5232,6 +5248,7 @@ BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, dont_flush, kDontFlush)
 BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_generator, kIsGenerator)
 
 void SharedFunctionInfo::BeforeVisitingPointers() {
+  if (IsInobjectSlackTrackingInProgress()) DetachInitialMap();
 }
 
 
@@ -5456,12 +5473,6 @@ bool JSFunction::IsInOptimizationQueue() {
 }
 
 
-bool JSFunction::IsInobjectSlackTrackingInProgress() {
-  return has_initial_map() &&
-      initial_map()->construction_count() != JSFunction::kNoSlackTracking;
-}
-
-
 Code* JSFunction::code() {
   return Code::cast(
       Code::GetObjectFromEntryAddress(FIELD_ADDR(this, kCodeEntryOffset)));