Add browser-compatible version.

lib/src/io.dart

Index: lib/src/io.dart
diff --git a/lib/src/io.dart b/lib/src/io.dart
index ff8761b7bbb788e1c166e8e8ab1b17ad91c8bbb7..cc17b5fd7afb3856d311aa48618c5f5b70a12bcb 100644
--- a/lib/src/io.dart
+++ b/lib/src/io.dart
@@ -1,14 +1,13 @@
-// 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.
 
-// dart:io based strategy for loading resources.
-
 import "dart:async" show Future, Stream;
 import "dart:convert" show Encoding, LATIN1, UTF8;
 import "dart:io" show
     File, HttpClient, HttpClientResponse, HttpClientRequest, HttpHeaders;
 import "dart:typed_data" show Uint8List;
+
 import "package:typed_data/typed_buffers.dart" show Uint8Buffer;
 
 /// Read the bytes of a URI as a stream of bytes.