1. Add user tag to the pointers traversed in the object store

runtime/vm/intrinsifier_ia32.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // The intrinsic code below is executed before a method has built its frame.
 // The return address is on the stack and the arguments below it.
 // Registers EDX (arguments descriptor) and ECX (function) must be preserved.
 // Each intrinsification method returns true if the corresponding
 // Dart method was intrinsified.
 
@@ skipping 1710 matching lines @@
   // Set Isolate::user_tag_.
   __ movl(user_tag_addr, EBX);
   __ ret();
 }
 
 
 void Intrinsifier::UserTag_defaultTag(Assembler* assembler) {
   Isolate* isolate = Isolate::Current();
   const Address default_tag_addr =
       Address::Absolute(
-          reinterpret_cast<uword>(isolate->object_store()) +
-                                  ObjectStore::default_tag_offset());
+          reinterpret_cast<uword>(isolate) + Isolate::default_tag_offset());
   // Set return value.
   __ movl(EAX, default_tag_addr);
   __ ret();
 }
 
 
 void Intrinsifier::Profiler_getCurrentTag(Assembler* assembler) {
   Isolate* isolate = Isolate::Current();
   const Address current_tag_addr =
       Address::Absolute(reinterpret_cast<uword>(isolate) +
                         Isolate::current_tag_offset());
   // Set return value to Isolate::current_tag_.
   __ movl(EAX, current_tag_addr);
   __ ret();
 }
 
 #undef __
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32