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

tests/corelib/uri_scheme_test.dart

Index: tests/corelib/uri_scheme_test.dart
diff --git a/tests/corelib/uri_scheme_test.dart b/tests/corelib/uri_scheme_test.dart
index 2a7fd764e126beca2a0c9d05eee14523e47fef0f..2565e70ab427372c705300c32c1ccc267d75e755 100644
--- a/tests/corelib/uri_scheme_test.dart
+++ b/tests/corelib/uri_scheme_test.dart
@@ -7,6 +7,8 @@ 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() {
@@ -21,6 +23,7 @@ void testScheme() {
   test("http+ssl", "http+ssl:", "HTTP+ssl");
   test("urn", "urn:", "urn");
   test("urn", "urn:", "UrN");
+  test("a123.432", "a123.432:", "a123.432");
 }
 
 main() {