Add data-URI support class to dart:core (next to Uri).

tests/lib/uri/uri_normalize_path_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 uriNormalizePathTest;
 
 import "package:expect/expect.dart";
 
 test(String path, String normalizedPath) {
   for (var scheme in ["http", "file", "unknown"]) {
@@ skipping 34 matching lines @@
   test("./../foo", "foo");
   test("./../", "");
   test("./../.", "");
   test("foo/bar/baz/../../../../qux", "/qux");
   test("/foo/bar/baz/../../../../qux", "/qux");
   test(".", "");
   test("..", "");
   test("/.", "/");
   test("/..", "/");
 }