Remove dead callback.

runtime/vm/isolate.h

 // 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.
 
 #ifndef VM_ISOLATE_H_
 #define VM_ISOLATE_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/atomic.h"
@@ skipping 819 matching lines @@
   int64_t last_reload_timestamp_;
 
 #define ISOLATE_METRIC_VARIABLE(type, variable, name, unit)                    \
   type metric_##variable##_;
   ISOLATE_METRIC_LIST(ISOLATE_METRIC_VARIABLE);
 #undef ISOLATE_METRIC_VARIABLE
 
 
   static Dart_IsolateCreateCallback create_callback_;
   static Dart_IsolateShutdownCallback shutdown_callback_;
-  static Dart_IsolateInterruptCallback vmstats_callback_;
 
   static void WakePauseEventHandler(Dart_Isolate isolate);
 
   // Manage list of existing isolates.
   static bool AddIsolateToList(Isolate* isolate);
   static void RemoveIsolateFromList(Isolate* isolate);
 
   // This monitor protects isolates_list_head_, and creation_enabled_.
   static Monitor* isolates_list_monitor_;
   static Isolate* isolates_list_head_;
@@ skipping 140 matching lines @@
   intptr_t* spawn_count_;
 
   Dart_IsolateFlags isolate_flags_;
   bool paused_;
   bool errors_are_fatal_;
 };
 
 }  // namespace dart
 
 #endif  // VM_ISOLATE_H_