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

src/factory.cc

 // Copyright 2014 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.
 
 #include "factory.h"
 
 #include "conversions.h"
 #include "isolate-inl.h"
 #include "macro-assembler.h"
 
@@ skipping 1914 matching lines @@
   share->set_scope_info(ScopeInfo::Empty(isolate()));
   Code* construct_stub =
       isolate()->builtins()->builtin(Builtins::kJSConstructStubGeneric);
   share->set_construct_stub(construct_stub);
   share->set_instance_class_name(*Object_string());
   share->set_function_data(*undefined_value(), SKIP_WRITE_BARRIER);
   share->set_script(*undefined_value(), SKIP_WRITE_BARRIER);
   share->set_debug_info(*undefined_value(), SKIP_WRITE_BARRIER);
   share->set_inferred_name(*empty_string(), SKIP_WRITE_BARRIER);
   share->set_feedback_vector(*empty_fixed_array(), SKIP_WRITE_BARRIER);
-  share->set_initial_map(*undefined_value(), SKIP_WRITE_BARRIER);
   share->set_profiler_ticks(0);
   share->set_ast_node_count(0);
   share->set_counters(0);
 
   // Set integer fields (smi or int, depending on the architecture).
   share->set_length(0);
   share->set_formal_parameter_count(0);
   share->set_expected_nof_properties(0);
   share->set_num_literals(0);
   share->set_start_position_and_type(0);
@@ skipping 386 matching lines @@
   return Handle<Object>::null();
 }
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return value ? true_value() : false_value();
 }
 
 
 } }  // namespace v8::internal