Un-hide the --hostname option for pub serve.

sdk/lib/_internal/pub/lib/src/command/serve.dart

Index: sdk/lib/_internal/pub/lib/src/command/serve.dart
diff --git a/sdk/lib/_internal/pub/lib/src/command/serve.dart b/sdk/lib/_internal/pub/lib/src/command/serve.dart
index f43cc3a4b1a6588237079b86617460089a4938a0..214edb13eb656d0b996054f8c84475dcc41b5262 100644
--- a/sdk/lib/_internal/pub/lib/src/command/serve.dart
+++ b/sdk/lib/_internal/pub/lib/src/command/serve.dart
@@ -44,16 +44,11 @@ class ServeCommand extends PubCommand {
   final _completer = new Completer();
 
   ServeCommand() {
+    commandParser.addOption('hostname', defaultsTo: 'localhost',
+        help: 'The hostname to listen on.');
     commandParser.addOption('port', defaultsTo: '8080',
         help: 'The base port to listen on.');
 
-    // A hidden option for the tests to work around a bug in some of the OS X
-    // bots where "localhost" very rarely resolves to the IPv4 loopback address
-    // instead of IPv6 (or vice versa). The tests will always set this to
-    // 127.0.0.1.
-    commandParser.addOption('hostname',
-                            defaultsTo: 'localhost',
-                            hide: true);
     commandParser.addFlag('dart2js', defaultsTo: true,
         help: 'Compile Dart to JavaScript.');
     commandParser.addFlag('force-poll', defaultsTo: false,