Make the http portion of the analysis server optional.

pkg/analysis_server/lib/driver.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library driver;
 
 import 'dart:io';
 
 import 'package:analysis_server/http_server.dart';
 import 'package:analysis_server/src/socket_server.dart';
@@ skipping 42 matching lines @@
         "print this help message without starting a server", defaultsTo: false,
         negatable: false);
     parser.addOption(PORT_OPTION, help:
         "[port] the port on which the server will listen");
 
     ArgResults results = parser.parse(args);
     if (results[HELP_OPTION]) {
       _printUsage(parser);
       return;
     }
-    if (results[PORT_OPTION] == null) {
-      print('Missing required port number');
-      print('');
-      _printUsage(parser);
-      exitCode = 1;
-      return;
+    int port;
+    bool serve_http = false;
+    if (results[PORT_OPTION] != null) {
+      serve_http = true;
+      try {
+        port = int.parse(results[PORT_OPTION]);
+      } on FormatException {
+        print('Invalid port number: ${results[PORT_OPTION]}');
+        print('');
+        _printUsage(parser);
+        exitCode = 1;
+        return;
+      }
     }
 
-    try {
-      int port = int.parse(results[PORT_OPTION]);
+    if (serve_http) {
       httpServer.serveHttp(port);
-    } on FormatException {
-      print('Invalid port number: ${results[PORT_OPTION]}');
-      print('');
-      _printUsage(parser);
-      exitCode = 1;
-      return;
     }
     stdioServer.serveStdio().then((_) {
-      httpServer.close();
+      if (serve_http) {
+        httpServer.close();
+      }
     });
   }
 
   /**
    * Print information about how to use the server.
    */
   void _printUsage(ArgParser parser) {
     print('Usage: $BINARY_NAME [flags]');
     print('');
     print('Supported flags are:');
     print(parser.getUsage());
   }
 }