Add a callback to inform embedders when an isolate is being shut down.

bin/gen_snapshot.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.
 
 // Generate a snapshot file after loading all the scripts specified on the
 // command line.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
@@ skipping 237 matching lines @@
   if (snapshot_filename == NULL) {
     fprintf(stderr, "No snapshot output file specified\n");
     return 255;
   }
 
   Dart_SetVMFlags(vm_options.count(), vm_options.arguments());
 
   // Initialize the Dart VM.
   // Note: We don't expect isolates to be created from dart code during
   // snapshot generation.
-  Dart_Initialize(NULL, NULL);
+  Dart_Initialize(NULL, NULL, NULL);
 
   char* error;
   Dart_Isolate isolate = Dart_CreateIsolate(NULL, NULL, NULL, NULL, &error);
   if (isolate == NULL) {
     fprintf(stderr, "%s", error);
     free(error);
     exit(255);
   }
 
   Dart_Handle result;
@@ skipping 51 matching lines @@
     exit(255);
   }
   // Now write the snapshot out to specified file and exit.
   WriteSnapshotFile(buffer, size);
   Dart_ExitScope();
 
   // Shutdown the isolate.
   Dart_ShutdownIsolate();
   return 0;
 }