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

runtime/bin/socket_fuchsia.cc

 // Copyright (c) 2016, 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.
 
 #if !defined(DART_IO_DISABLED)
 
 #include "platform/globals.h"
 #if defined(HOST_OS_FUCHSIA)
 
 #include "bin/socket.h"
@@ skipping 54 matching lines @@
 
 
 bool Socket::FormatNumericAddress(const RawAddr& addr, char* address, int len) {
   socklen_t salen = SocketAddress::GetAddrLength(addr);
   LOG_INFO("Socket::FormatNumericAddress: calling getnameinfo\n");
   return (NO_RETRY_EXPECTED(getnameinfo(&addr.addr, salen, address, len, NULL,
                                         0, NI_NUMERICHOST) == 0));
 }
 
 
+Socket::Socket(intptr_t fd)
+    : ReferenceCounted(), fd_(fd), port_(ILLEGAL_PORT) {}
+
+
+void Socket::SetClosedFd() {
+  fd_ = kClosedFd;
+}
+
+
 bool Socket::Initialize() {
   // Nothing to do on Fuchsia.
   return true;
 }
 
 
 static intptr_t Create(const RawAddr& addr) {
   LOG_INFO("Create: calling socket(SOCK_STREAM)\n");
   intptr_t fd = NO_RETRY_EXPECTED(socket(addr.ss.ss_family, SOCK_STREAM, 0));
   if (fd < 0) {
@@ skipping 445 matching lines @@
   UNIMPLEMENTED();
   return false;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(HOST_OS_FUCHSIA)
 
 #endif  // !defined(DART_IO_DISABLED)