Add browser-compatible version.

lib/src/browser/loader.dart

 // Copyright (c) 2015, 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:async" show Future, Stream;
 import "dart:convert" show Encoding;
 import "dart:isolate" show Isolate;
-import "io.dart" as io;  // TODO: make this import configuration dependent.
+
+import "html_io.dart" as io;
 
 /// Resource loading strategy.
 ///
 /// An abstraction of the functionality needed to load resources.
 ///
 /// Implementations of this interface decide which URI schemes they support.
 abstract class ResourceLoader {
   /// A resource loader that can load as many of the following URI
   /// schemes as are supported by the platform:
   /// * file
   /// * http
   /// * https
   /// * data
   /// * package
   ///
   /// (For example, file: URIs are not supported in the browser).
   /// Relative URI references are accepted - they are resolved against
   /// [Uri.base] before being loaded.
-  static const ResourceLoader defaultLoader = const PackageLoader();
+  static ResourceLoader get defaultLoader => const DefaultLoader();
 
   /// Reads the file located by [uri] as a stream of bytes.
   Stream<List<int>> openRead(Uri uri);
 
   /// Reads the file located by [uri] as a list of bytes.
   Future<List<int>> readAsBytes(Uri uri);
 
   /// Reads the file located by [uri] as a [String].
   ///
   /// The file bytes are decoded using [encoding], if provided.
   ///
   /// If [encoding] is omitted, the default for the `file:` scheme is UTF-8.
   /// For `http`, `https` and `data` URIs, the Content-Type header's charset
   /// is used, if available and recognized by [Encoding.getByName],
   /// otherwise it defaults to Latin-1 for `http` and `https`
   /// and to ASCII for `data` URIs.
   Future<String> readAsString(Uri uri, { Encoding encoding });
 }
 
-/// Default implementation of [ResourceLoader].
+/// Default implementation of [ResourceLoader]..
 ///
 /// Uses the system's available loading functionality to implement the
 /// loading functions.
 ///
-/// Supports `http:`, `https:`, `file:` and `data:` URIs.
+/// Supports as many of `http:`, `https:`, `file:` and `data:` URIs as
+/// possible.
 class DefaultLoader implements ResourceLoader {
   const DefaultLoader();
 
   Stream<List<int>> openRead(Uri uri) => io.readAsStream(uri);
 
   Future<List<int>> readAsBytes(Uri uri) => io.readAsBytes(uri);
 
   Future<String> readAsString(Uri uri, { Encoding encoding }) =>
       io.readAsString(uri, encoding);
 }
-
-
-/// Implementation of [ResourceLoader] that accepts relative and package: URIs.
-///
-/// Like [DefaultLoader] except that it resolves package URIs and relative
-/// URI references as well.
-///
-/// This class may be useful when you don't want to bother creating a [Resource]
-/// object, and just want to load a resource directly.
-class PackageLoader implements ResourceLoader {
-  const PackageLoader();
-
-  Stream<List<int>> openRead(Uri uri) async* {
-    yield* io.readAsStream(await resolveUri(uri));
-  }
-
-  Future<List<int>> readAsBytes(Uri uri) async =>
-      io.readAsBytes(await resolveUri(uri));
-
-  Future<String> readAsString(Uri uri, { Encoding encoding }) async =>
-      io.readAsString(await resolveUri(uri), encoding);
-}
-
-/// Helper function for resolving to a non-relative, non-package URI.
-Future<Uri> resolveUri(Uri uri) async {
-  if (uri.scheme == "package") {
-    return Isolate.resolvePackageUri(uri);
-  }
-  return Uri.base.resolveUri(uri);
-}