Add support for cloning server-sockets.

runtime/bin/socket.cc

 // Copyright (c) 2013, 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 "bin/io_buffer.h"
 #include "bin/isolate_data.h"
 #include "bin/socket.h"
 #include "bin/dartutils.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
@@ skipping 331 matching lines @@
 
 void FUNCTION_NAME(Socket_GetStdioHandle)(Dart_NativeArguments args) {
   int64_t num = DartUtils::GetInt64ValueCheckRange(
       Dart_GetNativeArgument(args, 1), 0, 2);
   intptr_t socket = Socket::GetStdioHandle(num);
   Socket::SetSocketIdNativeField(Dart_GetNativeArgument(args, 0), socket);
   Dart_SetReturnValue(args, Dart_NewBoolean(socket >= 0));
 }
 
 
+void FUNCTION_NAME(Socket_GetSocketId)(Dart_NativeArguments args) {
+  intptr_t id =
+      Socket::GetSocketIdNativeField(Dart_GetNativeArgument(args, 0));
+  Dart_SetReturnValue(args, Dart_NewInteger(id));
+}
+
+
 void FUNCTION_NAME(Socket_SetSocketId)(Dart_NativeArguments args) {
   intptr_t id =
       DartUtils::GetIntptrValue(Dart_GetNativeArgument(args, 1));
   Socket::SetSocketIdNativeField(Dart_GetNativeArgument(args, 0), id);
 }
 
 
 void FUNCTION_NAME(ServerSocket_CreateBindListen)(Dart_NativeArguments args) {
   RawAddr addr;
   SocketAddress::GetSockAddr(Dart_GetNativeArgument(args, 1), &addr);
@@ skipping 318 matching lines @@
 intptr_t Socket::GetSocketIdNativeField(Dart_Handle socket_obj) {
   intptr_t socket = 0;
   Dart_Handle err =
       Dart_GetNativeInstanceField(socket_obj, kSocketIdNativeField, &socket);
   if (Dart_IsError(err)) Dart_PropagateError(err);
   return socket;
 }
 
 }  // namespace bin
 }  // namespace dart