Wrap the http server start-up in an exception handler (issue 24363)

pkg/analysis_server/lib/src/server/http_server.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 http.server;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:analysis_server/src/channel/web_socket_channel.dart';
@@ skipping 58 matching lines @@
     if (_printBuffer.length > MAX_PRINT_BUFFER_LENGTH) {
       _printBuffer.removeRange(
           0, _printBuffer.length - MAX_PRINT_BUFFER_LENGTH);
     }
   }
 
   /**
    * Begin serving HTTP requests over the given port.
    */
   void serveHttp(int port) {
-    _server = HttpServer.bind(InternetAddress.LOOPBACK_IP_V4, port);
-    _server.then(_handleServer);
+    try {
+      _server = HttpServer.bind(InternetAddress.LOOPBACK_IP_V4, port);
+      _server.then(_handleServer);
+    } catch (exception) {
+      // We were unable to start the server, and there's nothing we can do about
+      // it.
+    }
   }
 
   /**
    * Handle a GET request received by the HTTP server.
    */
   void _handleGetRequest(HttpRequest request) {
     if (AnalysisEngine.instance.useTaskModel) {
       if (newGetHandler == null) {
         newGetHandler = new newHandler.GetHandler(socketServer, _printBuffer);
       }
@@ skipping 39 matching lines @@
    */
   void _returnUnknownRequest(HttpRequest request) {
     HttpResponse response = request.response;
     response.statusCode = HttpStatus.NOT_FOUND;
     response.headers.contentType =
         new ContentType("text", "plain", charset: "utf-8");
     response.write('Not found');
     response.close();
   }
 }