Add Resource package.

lib/src/io.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.
 
 // dart:io based strategy for loading resources.
 
-import "dart:io" show File, HttpClient, HttpClientRequest, HttpClientResponse;
 import "dart:async" show Future, Stream;
-import "dart:convert" show Encoding, UTF8;
+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.
 Stream<List<int>> readAsStream(Uri uri) async* {
   if (uri.scheme == "file") {
     yield* new File.fromUri(uri).openRead();
     return;
   }
   if (uri.scheme == "http" || uri.scheme == "https") {
     HttpClientResponse response = await _httpGet(uri);
     yield* response;
     return;
   }
+  if (uri.scheme == "data") {
+    yield uri.data.contentAsBytes();
+    return;
+  }
   throw new UnsupportedError("Unsupported scheme: $uri");
 }
 
+/// Read the bytes of a URI as a list of bytes.
 Future<List<int>> readAsBytes(Uri uri) async {
   if (uri.scheme == "file") {
     return new File.fromUri(uri).readAsBytes();
   }
   if (uri.scheme == "http" || uri.scheme == "https") {
     HttpClientResponse response = await _httpGet(uri);
     Uint8Buffer buffer = new Uint8Buffer();
     await for (var bytes in response) {
       buffer.addAll(bytes);
     }
     return buffer.toList();
   }
+  if (uri.scheme == "data") {
+    return uri.data.contentAsBytes();
+  }
   throw new UnsupportedError("Unsupported scheme: $uri");
 }
 
+/// Read the bytes of a URI as a string.
 Future<String> readAsString(Uri uri, Encoding encoding) async {
-  if (encoding == null) encoding = UTF8;
   if (uri.scheme == "file") {
+    if (encoding == null) encoding = UTF8;
     return new File.fromUri(uri).readAsString(encoding: encoding);
   }
   if (uri.scheme == "http" || uri.scheme == "https") {
-    HttpClientResponse response = await _httpGet(uri);
-    Uint8Buffer buffer = new Uint8Buffer();
-    await for (var bytes in response) {
-      buffer.addAll(bytes);
+    HttpClientRequest request = await new HttpClient().getUrl(uri);
+    // Prefer text/plain, text/* if possible, otherwise take whatever is there.
+    request.headers.set(HttpHeaders.ACCEPT, "text/plain, text/*, */*");
+    if (encoding != null) {
+      request.headers.set(HttpHeaders.ACCEPT_CHARSET, encoding.name);
     }
-    new String.fromCharCodes(buffer.toList());
+    HttpClientResponse response = await request.close();
+    encoding ??= Encoding.getByName(response.headers.contentType?.charset);
+    if (encoding == null || encoding == LATIN1) {
+      // Default to LATIN-1 if no encoding found.
+      // Special case LATIN-1 since it is common and doesn't need decoding.
+      int length = response.contentLength;
+      if (length < 0) length = 0;
+      Uint8Buffer buffer = new Uint8Buffer(length);
+      await for (var bytes in response) {
+        buffer.addAll(bytes);
+      }
+      var byteList = new Uint8List.view(buffer.buffer, 0, buffer.length);
+      return new String.fromCharCodes(byteList);
+    }
+    return response.transform(encoding.decoder).join();
+  }
+  if (uri.scheme == "data") {
+    return uri.data.contentAsString(encoding: encoding);
   }
   throw new UnsupportedError("Unsupported scheme: $uri");
 }
 
 Future<HttpClientResponse> _httpGet(Uri uri) async {
   HttpClientRequest request = await new HttpClient().getUrl(uri);
-  return await request.close();
+    request.headers.set(HttpHeaders.ACCEPT, "application/octet-stream, */*");
+  return request.close();
 }