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

tests/corelib/uri_scheme_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 "package:expect/expect.dart";
 
 void testInvalidArguments() {
   Expect.throws(() => new Uri(scheme: "_"), (e) => e is ArgumentError);
   Expect.throws(() => new Uri(scheme: "http_s"), (e) => e is ArgumentError);
+  Expect.throws(() => new Uri(scheme: "127.0.0.1:80"),
+                (e) => e is ArgumentError);
 }
 
 void testScheme() {
   test(String expectedScheme, String expectedUri, String scheme) {
     var uri = new Uri(scheme: scheme);
     Expect.equals(expectedScheme, uri.scheme);
     Expect.equals(expectedUri, uri.toString());
   }
 
   test("http", "http:", "http");
   test("http", "http:", "HTTP");
   test("http+ssl", "http+ssl:", "HTTP+ssl");
   test("urn", "urn:", "urn");
   test("urn", "urn:", "UrN");
+  test("a123.432", "a123.432:", "a123.432");
 }
 
 main() {
   testInvalidArguments();
   testScheme();
 }