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

runtime/vm/snapshot.h

 // 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.
 
 #ifndef RUNTIME_VM_SNAPSHOT_H_
 #define RUNTIME_VM_SNAPSHOT_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/bitfield.h"
@@ skipping 824 matching lines @@
   // Snapshot kind.
   Snapshot::Kind kind() const { return kind_; }
   Thread* thread() const { return thread_; }
   Zone* zone() const { return thread_->zone(); }
   Isolate* isolate() const { return thread_->isolate(); }
   Heap* heap() const { return isolate()->heap(); }
 
   // Serialize an object into the buffer.
   void WriteObject(RawObject* raw);
 
-  uword GetObjectTags(RawObject* raw);
+  static uint32_t GetObjectTags(RawObject* raw);
+  static uword GetObjectTagsAndHash(RawObject* raw);
 
   Exceptions::ExceptionType exception_type() const { return exception_type_; }
   void set_exception_type(Exceptions::ExceptionType type) {
     exception_type_ = type;
   }
   const char* exception_msg() const { return exception_msg_; }
   void set_exception_msg(const char* msg) { exception_msg_ = msg; }
   bool can_send_any_object() const { return can_send_any_object_; }
   void ThrowException(Exceptions::ExceptionType type, const char* msg);
 
@@ skipping 158 matching lines @@
  private:
   SnapshotWriter* writer_;
   bool as_references_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapshotWriterVisitor);
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_SNAPSHOT_H_