Update pub usage of '127.0.0.1'.

sdk/lib/_internal/pub/lib/src/safe_http_server.dart

Index: sdk/lib/_internal/pub/lib/src/safe_http_server.dart
diff --git a/sdk/lib/_internal/pub/lib/src/safe_http_server.dart b/sdk/lib/_internal/pub/lib/src/safe_http_server.dart
index 2c193681045583de7d9e94263bb34495f5167576..25d57ee6bbef77bc4dfb63d532a73731a77847dd 100644
--- a/sdk/lib/_internal/pub/lib/src/safe_http_server.dart
+++ b/sdk/lib/_internal/pub/lib/src/safe_http_server.dart
@@ -21,7 +21,7 @@ import 'dart:uri';
 class SafeHttpServer extends StreamView<HttpRequest> implements HttpServer {
   final HttpServer _inner;
 
-  static Future<SafeHttpServer> bind([String host = "127.0.0.1",
+  static Future<SafeHttpServer> bind([String host = "localhost",
       int port = 0, int backlog = 0]) {
     return HttpServer.bind(host, port, backlog: backlog)
         .then((server) => new SafeHttpServer(server));