don't use default isolate in mksnapshot

src/mksnapshot.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 292 matching lines @@
   fprintf(stderr, "%s\n", *message_line);
   for (int i = 0; i <= message->GetEndColumn(); ++i) {
     fprintf(stderr, "%c", i < message->GetStartColumn() ? ' ' : '^');
   }
   fprintf(stderr, "\n");
 }
 
 
 int main(int argc, char** argv) {
   V8::InitializeICU();
+  i::Isolate::SetCrashIfDefaultIsolateInitialized();
 
   // By default, log code create information in the snapshot.
   i::FLAG_log_code = true;
 
   // Print the usage if an error occurs when parsing the command line
   // flags or if the help flag is set.
   int result = i::FlagList::SetFlagsFromCommandLine(&argc, argv, true);
   if (result > 0 || argc != 2 || i::FLAG_help) {
     ::printf("Usage: %s [flag] ... outfile\n", argv[0]);
     i::FlagList::PrintHelp();
     return !i::FLAG_help;
   }
 #ifdef COMPRESS_STARTUP_DATA_BZ2
   BZip2Decompressor natives_decompressor;
   int bz2_result = natives_decompressor.Decompress();
   if (bz2_result != BZ_OK) {
     fprintf(stderr, "bzip error code: %d\n", bz2_result);
     exit(1);
   }
 #endif
-  Isolate* isolate = Isolate::GetCurrent();
+  i::FLAG_logfile_per_isolate = false;
+
+  Isolate* isolate = v8::Isolate::New();
+  isolate->Enter();
   i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
   i::Serializer::Enable(internal_isolate);
   Persistent<Context> context;
   {
     HandleScope handle_scope(isolate);
     context.Reset(isolate, Context::New(isolate));
   }
 
   if (context.IsEmpty()) {
     fprintf(stderr,
@@ skipping 89 matching lines @@
       "",
       ser.CurrentAllocationAddress(i::NEW_SPACE),
       ser.CurrentAllocationAddress(i::OLD_POINTER_SPACE),
       ser.CurrentAllocationAddress(i::OLD_DATA_SPACE),
       ser.CurrentAllocationAddress(i::CODE_SPACE),
       ser.CurrentAllocationAddress(i::MAP_SPACE),
       ser.CurrentAllocationAddress(i::CELL_SPACE),
       ser.CurrentAllocationAddress(i::PROPERTY_CELL_SPACE));
   return 0;
 }