Default to "127.0.0.1" in pub serve.

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

Index: sdk/lib/_internal/pub/lib/src/utils.dart
diff --git a/sdk/lib/_internal/pub/lib/src/utils.dart b/sdk/lib/_internal/pub/lib/src/utils.dart
index 7e5d92f03bbd0ef2409cbb8d8937e5ec5fb32a4d..931b1770e67280bfe81f3fb11e55df0909f2256a 100644
--- a/sdk/lib/_internal/pub/lib/src/utils.dart
+++ b/sdk/lib/_internal/pub/lib/src/utils.dart
@@ -15,6 +15,7 @@ import 'dart:mirrors';
 import "package:analyzer/analyzer.dart";
 import "package:crypto/crypto.dart";
 import 'package:path/path.dart' as path;
+import "package:stack_trace/stack_trace.dart";
 
 import 'dart.dart';
 
@@ -112,6 +113,19 @@ String pluralize(String name, int number, {String plural}) {
   return '${name}s';
 }
 
+/// Creates a URL string for [address]:[port].
+///
+/// Handles properly formatting IPv6 addresses.
+String baseUrlForAddress(InternetAddress address, int port) {
+  // IPv6 addresses in URLs need to be enclosed in square brackets to avoid
+  // URL ambiguity with the ":" in the address.
+  if (address.type == InternetAddressType.IP_V6) {
+    return "http://[${address.address}]:$port";
+  }
+
+  return "http://${address.address}:$port";
+}
+
 /// Flattens nested lists inside an iterable into a single list containing only
 /// non-list elements.
 List flatten(Iterable nested) {