[dart:io] Adds a finalizer to _NativeSocket to avoid socket leaks

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 1251 matching lines @@
     delete[] isolate_name;
     Log::PrintErr("%s\n", error);
     free(error);
     error = NULL;
     Process::TerminateExitCodeHandler();
     error = Dart_Cleanup();
     if (error != NULL) {
       Log::PrintErr("VM cleanup failed: %s\n", error);
       free(error);
     }
+    Process::ClearAllSignalHandlers();
     EventHandler::Stop();
     Platform::Exit((exit_code != 0) ? exit_code : kErrorExitCode);
   }
   main_isolate = isolate;
   delete[] isolate_name;
 
   Dart_EnterIsolate(isolate);
   ASSERT(isolate == Dart_CurrentIsolate());
   ASSERT(isolate != NULL);
   Dart_Handle result;
@@ skipping 398 matching lines @@
   }
 
   // Terminate process exit-code handler.
   Process::TerminateExitCodeHandler();
 
   error = Dart_Cleanup();
   if (error != NULL) {
     Log::PrintErr("VM cleanup failed: %s\n", error);
     free(error);
   }
+  Process::ClearAllSignalHandlers();
   EventHandler::Stop();
 
   delete app_snapshot;
   free(app_script_uri);
 
   // Free copied argument strings if converted.
   if (argv_converted) {
     for (int i = 0; i < argc; i++) {
       free(argv[i]);
     }
@@ skipping 12 matching lines @@
   Platform::Exit(Process::GlobalExitCode());
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   dart::bin::main(argc, argv);
   UNREACHABLE();
 }