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

runtime/vm/object_test.cc

 // Copyright (c) 2012, 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.
 
 #include "platform/globals.h"
 
 #include "vm/assembler.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
@@ skipping 4337 matching lines @@
     elideSubstring("_InternalLinkedHashMap@", buffer, buffer);
     EXPECT_STREQ(
         "{\"type\":\"@Instance\",\"_vmType\":\"@LinkedHashMap\","
         "\"class\":{\"type\":\"@Class\",\"id\":\"\","
         "\"name\":\"_InternalLinkedHashMap\",\"_vmName\":\"\"},\"id\":\"\"}",
         buffer);
   }
   // UserTag reference
   {
     JSONStream js;
-    Instance& tag = Instance::Handle(isolate->object_store()->default_tag());
+    Instance& tag = Instance::Handle(isolate->default_tag());
     tag.PrintJSON(&js, true);
     elideSubstring("classes", js.ToCString(), buffer);
     elideSubstring("objects", buffer, buffer);
     elideSubstring("_UserTag@", buffer, buffer);
     EXPECT_STREQ(
         "{\"type\":\"@Instance\",\"_vmType\":\"@UserTag\","
         "\"class\":{\"type\":\"@Class\",\"id\":\"\",\"name\":\"_UserTag\","
         "\"_vmName\":\"\"},"
         "\"id\":\"\"}",
         buffer);
@@ skipping 102 matching lines @@
   EXPECT_VALID(h_result);
   Integer& result = Integer::Handle();
   result ^= Api::UnwrapHandle(h_result);
   String& foo = String::Handle(String::New("foo"));
   Integer& expected = Integer::Handle();
   expected ^= foo.HashCode();
   EXPECT(result.IsIdenticalTo(expected));
 }
 
 }  // namespace dart