VM: Reland Inline instance object hash code into object header on 64bit.

runtime/vm/heap.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 "vm/heap.h"
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/flags.h"
 #include "vm/isolate.h"
@@ skipping 647 matching lines @@
       UNREACHABLE();
       return "";
   }
 }
 
 
 int64_t Heap::PeerCount() const {
   return new_weak_tables_[kPeers]->count() + old_weak_tables_[kPeers]->count();
 }
 
-
+#if !defined(HASH_IN_OBJECT_HEADER)
 int64_t Heap::HashCount() const {
   return new_weak_tables_[kHashes]->count() +
          old_weak_tables_[kHashes]->count();
 }
+#endif
 
 
 int64_t Heap::ObjectIdCount() const {
   return new_weak_tables_[kObjectIds]->count() +
          old_weak_tables_[kObjectIds]->count();
 }
 
 
 void Heap::ResetObjectIdTable() {
   new_weak_tables_[kObjectIds]->Reset();
@@ skipping 194 matching lines @@
   Dart::vm_isolate()->heap()->WriteProtect(false);
 }
 
 
 WritableVMIsolateScope::~WritableVMIsolateScope() {
   ASSERT(Dart::vm_isolate()->heap()->UsedInWords(Heap::kNew) == 0);
   Dart::vm_isolate()->heap()->WriteProtect(true);
 }
 
 }  // namespace dart