Fix another issue with r13348

runtime/bin/http_impl.dart

 // Copyright (c) 2012, 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.
 
 class _HttpHeaders implements HttpHeaders {
   _HttpHeaders() : _headers = new Map<String, List<String>>();
 
   List<String> operator[](String name) {
     name = name.toLowerCase();
     return _headers[name];
@@ skipping 1993 matching lines @@
           proxies.add(new _Proxy(host, port));
         } else if (proxy.trim() == DIRECT_PREFIX) {
           proxies.add(new _Proxy.direct());
         } else {
           throw new HttpException("Invalid proxy configuration $configuration");
         }
       }
     });
   }
   const _ProxyConfiguration.direct()
-      : proxies = [const _Proxy.direct()];
+      : proxies = const [const _Proxy.direct()];
 
   final List<_Proxy> proxies;
 }
 
 class _Proxy {
   const _Proxy(this.host, this.port) : isDirect = false;
   const _Proxy.direct() : host = null, port = null, isDirect = true;
 
   final String host;
   final int port;
@@ skipping 247 matching lines @@
 
 
 class _RedirectInfo implements RedirectInfo {
   const _RedirectInfo(int this.statusCode,
                       String this.method,
                       Uri this.location);
   final int statusCode;
   final String method;
   final Uri location;
 }