Add member localHostname() to the Dart IO Platform class.

runtime/bin/platform_win.cc

 // Copyright (c) 2011, 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/platform.h"
+#include "bin/socket.h"
 
 
 bool Platform::Initialize() {
   // Nothing to do on Windows.
   return true;
 }
 
 
 int Platform::NumberOfProcessors() {
   SYSTEM_INFO info;
   GetSystemInfo(&info);
   return info.dwNumberOfProcessors;
 }
 
 
 const char* Platform::OperatingSystem() {
   return "windows";
 }
 
 
+bool Platform::LocalHostname(char *buffer, intptr_t buffer_length) {
+  static bool socketInitialized = false;
+  if (!socketInitialized) {
+    // Initialize Socket for gethostname.
+    if (!Socket::Initialize()) return false;
+    socketInitialized = true;
+  }
+  return gethostname(buffer, buffer_length) == 0;
+}
+
+
 char* Platform::StrError(int error_code) {
   static const int kBufferSize = 1024;
   char* error = static_cast<char*>(malloc(kBufferSize));
   DWORD message_size =
       FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                     NULL,
                     error_code,
                     MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                     error,
                     kBufferSize,
                     NULL);
   if (message_size == 0) {
     if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
       fprintf(stderr, "FormatMessage failed %d\n", GetLastError());
     }
     snprintf(error, kBufferSize, "OS Error %d", error_code);
   }
   // Strip out \r\n at the end of the generated message and ensure
   // null termination.
   if (message_size > 2 &&
       error[message_size - 2] == '\r' &&
       error[message_size - 1] == '\n') {
     error[message_size - 2] = '\0';
   } else {
     error[kBufferSize - 1] = '\0';
   }
   return error;
 }