Add browser-compatible version.

lib/browser_resource.dart

-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2016, 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.
 
 /// A [Resource] is data that can be read into a Dart program.
 ///
 /// A resource is identified by a URI. It can be loaded as bytes or data.
 /// The resource URI may be a `package:` URI.
 ///
 /// Example:
 ///
 ///     var resource = new Resource("package:foo/foo_data.txt");
 ///     var string = await resource.readAsString(UTF8);
 ///     print(string);
 ///
 /// Example:
 ///
 ///     var resource = new Resource("http://example.com/data.json");
 ///     var obj = await resource.openRead()   // Reads as stream of bytes.
 ///                             .transform(UTF8.fuse(JSON).decoder)
 ///                             .first;
 ///
 ///
-/// Notice: Currently this package requires `dart:io` to do the reading,
-/// so it doesn't work in the browser.
+/// Notice: Currently this library requires `dart:Html` to do the reading,
+/// so it doesn't work outside of a browser.
+/// This library will eventually be mergeded into the `resource.dart` when
+/// features are available to make that possible.
 library resource;
 
-export "src/resource.dart" show Resource;
-export "src/loader.dart" show ResourceLoader;
+export "src/browser/resource.dart" show Resource;
+export "src/browser/loader.dart" show ResourceLoader;