[dart:io] Reland: Adds Platform.localeName

runtime/bin/platform_win.cc

Index: runtime/bin/platform_win.cc
diff --git a/runtime/bin/platform_win.cc b/runtime/bin/platform_win.cc
index 18526517e9ff2bd72c742d36a6a46bfdd3d30805..8ec32d24e1d9c23cf1d493f5dc3e2689692eab76 100644
--- a/runtime/bin/platform_win.cc
+++ b/runtime/bin/platform_win.cc
@@ -198,6 +198,16 @@ const char* Platform::LibraryExtension() {
 }
 
 
+const char* Platform::LocaleName() {
+  wchar_t locale_name[LOCALE_NAME_MAX_LENGTH];
+  int result = GetUserDefaultLocaleName(locale_name, LOCALE_NAME_MAX_LENGTH);
+  if (result == 0) {
+    return NULL;
+  }
+  return StringUtilsWin::WideToUtf8(locale_name);
+}
+
+
 bool Platform::LocalHostname(char* buffer, intptr_t buffer_length) {
 #if defined(DART_IO_DISABLED) || defined(PLATFORM_DISABLE_SOCKET)
   return false;