Fix bug in HTTP client request generation

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 1657 matching lines @@
   void _writeHeader() {
     List<int> data;
 
     // Write request line.
     data = _method.toString().charCodes();
     _httpConnection._write(data);
     _writeSP();
     // Send the path for direct connections and the whole URL for
     // proxy connections.
     if (!_connection._usingProxy) {
-      String path;
+      String path = _uri.path;
+      if (path.length == 0) path = "/";
       if (_uri.query != "") {
         if (_uri.fragment != "") {
-          path = "${_uri.path}?${_uri.query}#${_uri.fragment}";
+          path = "${path}?${_uri.query}#${_uri.fragment}";
         } else {
-          path = "${_uri.path}?${_uri.query}";
+          path = "${path}?${_uri.query}";
         }
-      } else {
-         path = _uri.path;
       }
       data = path.charCodes();
     } else {
       data = _uri.toString().charCodes();
     }
     _httpConnection._write(data);
     _writeSP();
     _httpConnection._write(_Const.HTTP11);
     _writeCRLF();
 
@@ skipping 650 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;
 }