Fixes leak of native File objects.

runtime/bin/main.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.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "include/dart_api.h"
 #include "include/dart_tools_api.h"
@@ skipping 1087 matching lines @@
   if (write_magic_number) {
     // Write the magic number to indicate file is a script snapshot.
     DartUtils::WriteMagicNumber(file);
   }
 
   if (!file->WriteFully(buffer, size)) {
     ErrorExit(kErrorExitCode,
               "Unable to open file %s for writing snapshot\n",
               qualified_filename);
   }
-  delete file;
+  file->Release();
   if (concat != NULL) {
     delete concat;
   }
 }
 
 
 static void ReadSnapshotFile(const char* snapshot_directory,
                              const char* filename,
                              const uint8_t** buffer) {
   char* concat = NULL;
@@ skipping 586 matching lines @@
   Platform::Exit(Process::GlobalExitCode());
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   dart::bin::main(argc, argv);
   UNREACHABLE();
 }