Revert "Clear isolate callback data before running shutdowncallback"

runtime/vm/dart.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.
 
 #include "vm/dart.h"
 
 #include "vm/become.h"
 #include "vm/clustered_snapshot.h"
 #include "vm/code_observers.h"
 #include "vm/cpu.h"
@@ skipping 651 matching lines @@
 #endif
   }
 
   return buffer.Steal();
 }
 
 
 void Dart::RunShutdownCallback() {
   Isolate* isolate = Isolate::Current();
   void* callback_data = isolate->init_callback_data();
-  // Clear the data from the isolate so future accesses will see NULL.
-  isolate->set_init_callback_data(NULL);
   Dart_IsolateShutdownCallback callback = Isolate::ShutdownCallback();
   if (callback != NULL) {
     (callback)(callback_data);
   }
 }
 
 
 void Dart::ShutdownIsolate(Isolate* isolate) {
   ASSERT(Isolate::Current() == NULL);
   // We need to enter the isolate in order to shut it down.
@@ skipping 38 matching lines @@
   return predefined_handles_->handles_.IsValidScopedHandle(address);
 }
 
 
 bool Dart::IsReadOnlyApiHandle(Dart_Handle handle) {
   ASSERT(predefined_handles_ != NULL);
   return predefined_handles_->api_handles_.IsValidHandle(handle);
 }
 
 }  // namespace dart