Return the correct port from Uri, when port is 0 and scheme is either http or https.

tests/corelib/uri_path_test.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.
 
 import "dart:collection";
 
 import "package:expect/expect.dart";
 
 void testInvalidArguments() {
 }
@@ skipping 29 matching lines @@
 void testPathSegments() {
   void test(String path, List<String> segments) {
     void check(uri) {
       Expect.equals(path, uri.path);
       Expect.equals(path, uri.toString());
       Expect.listEquals(segments, uri.pathSegments);
     }
 
     var uri1 = new Uri(pathSegments: segments);
     var uri2 = new Uri(path: path);
-    var uri3 = Uri.parse(path);
     check(uri1);
     check(uri2);
-    check(uri3);
-    Expect.equals(uri1, uri3);
-    Expect.equals(uri2, uri3);
+    Expect.equals(uri1, uri2);
   }
 
   test("", []);
   test("%20", [" "]);
   test("%20/%20%20", [" ", "  "]);
   test("A", ["A"]);
   test("%C3%B8", ["ø"]);
   test("%C3%B8/%C3%A5", ["ø", "å"]);
   test("%C8%A4/%E5%B9%B3%E4%BB%AE%E5%90%8D", ["Ȥ", "平仮名"]);
   test("A/b", ["A", "b"]);
@@ skipping 119 matching lines @@
   test(new Uri(pathSegments: ["a", "b"]).pathSegments);
 }
 
 main() {
   testInvalidArguments();
   testPath();
   testPathSegments();
   testPathCompare();
   testPathSegmentsUnmodifiableList();
 }