Allow proxy settings in environment variables to be full URLs

sdk/lib/io/http_impl.dart

 // Copyright (c) 2013, 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.
 
 part of dart.io;
 
 class _HttpIncoming extends Stream<List<int>> {
   final int _transferLength;
   final Completer _dataCompleter = new Completer();
   Stream<List<int>> _stream;
@@ skipping 1572 matching lines @@
       }
       return null;
     }
 
     checkProxy(String option) {
       if (option == null) return null;
       int pos = option.indexOf("://");
       if (pos >= 0) {
         option = option.substring(pos + 3);
       }
+      pos = option.indexOf("/");
+      if (pos >= 0) {
+        option = option.substring(0, pos);
+      }
       if (option.indexOf(":") == -1) option = "$option:1080";
       return "PROXY $option";
     }
 
     // Default to using the process current environment.
     if (environment == null) environment = Platform.environment;
 
     String proxyCfg;
 
     String noProxy = environment["no_proxy"];
@@ skipping 628 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;
 }