Add "toString()" to BaseRequest.

pkg/http/test/request_test.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.
 
 library request_test;
 
 import 'dart:io';
 
 import '../../unittest/lib/unittest.dart';
 import '../lib/http.dart' as http;
@@ skipping 369 matching lines @@
       expect(request.bodyFields, equals({"hello": "world"}));
       expect(() => request.bodyFields = {}, throwsStateError);
     });
 
     test("can't be called twice", () {
       var request = new http.Request('POST', dummyUrl);
       request.finalize();
       expect(request.finalize, throwsStateError);
     });
   });
+
+  group('#toString()', () {
+    test('includes the method and URL', () {
+      var request = new http.Request('POST', dummyUrl);
+      expect(request.toString(), 'POST $dummyUrl');
+    });
+  });
 }