Make the proxy server resolution from environment variables the default for HttpClient

sdk/lib/io/http.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;
 
 /**
  * HTTP status codes.
  */
 abstract class HttpStatus {
@@ skipping 751 matching lines @@
 
 
 /**
  * HTTP client factory. The [HttpClient] handles all the sockets associated
  * with the [HttpClientConnection]s and when the endpoint supports it, it will
  * try to reuse opened sockets for several requests to support HTTP 1.1
  * persistent connections. This means that sockets will be kept open for some
  * time after a requests have completed, unless HTTP procedures indicate that it
  * must be closed as part of completing the request. Use [:HttpClient.close:]
  * to force close the idle sockets.
+ *
+ * By default the HttpClient uses the proxy configuration available
+ * from the environment, see [findProxyFromEnvironment]. To turn off
+ * the use of proxies all together set the [findProxy] property to
+ * [:null:].
+ *
+ *     HttpClient client = new HttpClient();
+ *     client.findProxy = null;
  */
 abstract class HttpClient {
   static const int DEFAULT_HTTP_PORT = 80;
   static const int DEFAULT_HTTPS_PORT = 443;
 
   factory HttpClient() => new _HttpClient();
 
   /**
    * Opens a HTTP connection. The returned [HttpClientRequest] is used to
    * fill in the content of the request before sending it. The 'host' header for
@@ skipping 437 matching lines @@
 class RedirectLimitExceededException extends RedirectException {
   const RedirectLimitExceededException(List<RedirectInfo> redirects)
       : super("Redirect limit exceeded", redirects);
 }
 
 
 class RedirectLoopException extends RedirectException {
   const RedirectLoopException(List<RedirectInfo> redirects)
       : super("Redirect loop detected", redirects);
 }