Make failing HTTP requests thrown when using dart:io.

lib/src/io_io.dart

 // 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.
 
 import "dart:async" show Future, Stream;
 import "dart:convert" show Encoding, LATIN1, UTF8;
-import "dart:io" show
-    File, HttpClient, HttpClientResponse, HttpClientRequest, HttpHeaders;
+import "dart:io" show File,
+                      HttpStatus,
+                      HttpClient,
+                      HttpClientResponse,
+                      HttpClientRequest,
+                      HttpHeaders;
 
 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 _httpGetBytes(uri);
+    _throwIfFailed(response, 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 _httpGetBytes(uri);
+    _throwIfFailed(response, uri);
     int length = response.contentLength;
     if (length < 0) length = 0;
     var buffer = new Uint8Buffer(length);
     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 (uri.scheme == "file") {
     if (encoding == null) encoding = UTF8;
     return new File.fromUri(uri).readAsString(encoding: encoding);
   }
   if (uri.scheme == "http" || uri.scheme == "https") {
     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);
     }
     HttpClientResponse response = await request.close();
+    _throwIfFailed(response, uri);
     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;
       var buffer = new Uint8Buffer(length);
       await for (var bytes in response) {
         buffer.addAll(bytes);
       }
       var byteList = buffer.buffer.asUint8List(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> _httpGetBytes(Uri uri) async {
   HttpClientRequest request = await new HttpClient().getUrl(uri);
     request.headers.set(HttpHeaders.ACCEPT, "application/octet-stream, */*");
   return request.close();
 }
+
+void _throwIfFailed(HttpClientResponse response, Uri uri) {
+  var statusCode = response.statusCode;
+  if (statusCode < HttpStatus.OK || statusCode > HttpStatus.NO_CONTENT) {
+    throw new HttpException(response.reasonPhrase, uri: uri);
+  }
+}