[dart:io] Reland: Adds Platform.localeName

runtime/bin/platform.cc

Index: runtime/bin/platform.cc
diff --git a/runtime/bin/platform.cc b/runtime/bin/platform.cc
index e8b7849147fff3ce403f356381af03ea9930b864..bfe107fc1a6068db0c698b153ee33fce9edd7016 100644
--- a/runtime/bin/platform.cc
+++ b/runtime/bin/platform.cc
@@ -109,6 +109,16 @@ void FUNCTION_NAME(Platform_GetVersion)(Dart_NativeArguments args) {
   Dart_SetReturnValue(args, Dart_NewStringFromCString(Dart_VersionString()));
 }
 
+
+void FUNCTION_NAME(Platform_LocaleName)(Dart_NativeArguments args) {
+  const char* locale = Platform::LocaleName();
+  if (locale == NULL) {
+    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+  } else {
+    Dart_SetReturnValue(args, Dart_NewStringFromCString(locale));
+  }
+}
+
 }  // namespace bin
 }  // namespace dart