diff --git a/pkg/analyzer_experimental/bin/analyzer.dart b/pkg/analyzer_experimental/bin/analyzer.dart
index 119376f..d3c59f3 100644
--- a/pkg/analyzer_experimental/bin/analyzer.dart
+++ b/pkg/analyzer_experimental/bin/analyzer.dart
@@ -80,7 +80,7 @@
     ErrorSeverity batchResult = ErrorSeverity.NONE;
     // read line from stdin
     Stream cmdLine = stdin
-        .transform(new StringDecoder())
+        .transform(UTF8.decoder)
         .transform(new LineSplitter());
     var subscription = cmdLine.listen((String line) {
       // may be finish
diff --git a/pkg/analyzer_experimental/bin/formatter.dart b/pkg/analyzer_experimental/bin/formatter.dart
index dd25180..5673426 100755
--- a/pkg/analyzer_experimental/bin/formatter.dart
+++ b/pkg/analyzer_experimental/bin/formatter.dart
@@ -37,7 +37,7 @@
   var buffer = new StringBuffer();
   var file = new File(path);
   file.openRead()
-      .transform(new StringDecoder())
+      .transform(UTF8.decoder)
       .listen((data) =>  buffer.write(data),
         onError: (error) => print('Error, could not open "$path"'),
         onDone: () => print(_formatCU(buffer.toString())));
diff --git a/pkg/barback/lib/src/asset.dart b/pkg/barback/lib/src/asset.dart
index 05a2202..db7a5ea 100644
--- a/pkg/barback/lib/src/asset.dart
+++ b/pkg/barback/lib/src/asset.dart
@@ -5,6 +5,7 @@
 library barback.asset;
 
 import 'dart:async';
+import 'dart:convert' show Encoding, UTF8;
 import 'dart:io';
 import 'dart:utf';
 
@@ -37,7 +38,7 @@
   ///
   /// If the asset was created from a [String] the original string is always
   /// returned and [encoding] is ignored. Otherwise, the binary data of the
-  /// asset is decoded using [encoding], which defaults to [Encoding.UTF_8].
+  /// asset is decoded using [encoding], which defaults to [UTF8].
   Future<String> readAsString({Encoding encoding});
 
   /// Streams the binary contents of the asset.
@@ -54,16 +55,9 @@
       : super(id);
 
   Future<String> readAsString({Encoding encoding}) {
-    if (encoding == null) encoding = Encoding.UTF_8;
+    if (encoding == null) encoding = UTF8;
 
-    // TODO(rnystrom): When #6284 is fixed, just use that. Until then, only
-    // UTF-8 is supported. :(
-    if (encoding != Encoding.UTF_8) {
-      throw new UnsupportedError(
-          "${encoding.name} is not a supported encoding.");
-    }
-
-    return new Future.value(decodeUtf8(_contents));
+    return new Future.value(encoding.decode(_contents));
   }
 
   Stream<List<int>> read() => new Future<List<int>>.value(_contents).asStream();
@@ -104,7 +98,7 @@
       : super(id);
 
   Future<String> readAsString({Encoding encoding}) {
-    if (encoding == null) encoding = Encoding.UTF_8;
+    if (encoding == null) encoding = UTF8;
     return _file.readAsString(encoding: encoding);
   }
 
diff --git a/pkg/barback/test/asset_test.dart b/pkg/barback/test/asset_test.dart
index 395dbfd..b26d462 100644
--- a/pkg/barback/test/asset_test.dart
+++ b/pkg/barback/test/asset_test.dart
@@ -5,6 +5,7 @@
 library barback.test.asset_test;
 
 import 'dart:async';
+import 'dart:convert' show Encoding, UTF8, LATIN1;
 import 'dart:io';
 import 'dart:utf';
 
@@ -108,7 +109,7 @@
 
       test("supports UTF-8", () {
         var asset = new Asset.fromBytes(id, encodeUtf8("çøñ†éℵ™"));
-        expect(asset.readAsString(encoding: Encoding.UTF_8),
+        expect(asset.readAsString(encoding: UTF8),
             completion(equals("çøñ†éℵ™")));
       });
 
@@ -124,7 +125,7 @@
 
       test("ignores the encoding", () {
         var asset = new Asset.fromString(id, "contents");
-        expect(asset.readAsString(encoding: Encoding.ISO_8859_1),
+        expect(asset.readAsString(encoding: LATIN1),
             completion(equals("contents")));
       });
     });
diff --git a/pkg/barback/test/utils.dart b/pkg/barback/test/utils.dart
index 73f4f8b..1ee03ff 100644
--- a/pkg/barback/test/utils.dart
+++ b/pkg/barback/test/utils.dart
@@ -6,6 +6,7 @@
 
 import 'dart:async';
 import 'dart:collection';
+import 'dart:convert' show Encoding;
 import 'dart:io';
 
 import 'package:barback/barback.dart';
diff --git a/pkg/http/lib/src/byte_stream.dart b/pkg/http/lib/src/byte_stream.dart
index 20f78747..c75654a 100644
--- a/pkg/http/lib/src/byte_stream.dart
+++ b/pkg/http/lib/src/byte_stream.dart
@@ -5,6 +5,7 @@
 library byte_stream;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
 
@@ -30,10 +31,10 @@
   }
 
   /// Collect the data of this stream in a [String], decoded according to
-  /// [encoding], which defaults to `Encoding.UTF_8`.
-  Future<String> bytesToString([Encoding encoding=Encoding.UTF_8]) =>
-      toBytes().then((bytes) => decodeString(bytes, encoding));
+  /// [encoding], which defaults to `UTF8`.
+  Future<String> bytesToString([Encoding encoding=UTF8]) =>
+      toBytes().then((bytes) => encoding.decode(bytes));
 
-  Stream<String> toStringStream([Encoding encoding=Encoding.UTF_8]) =>
-    transform(new StringDecoder(encoding));
+  Stream<String> toStringStream([Encoding encoding=UTF8]) =>
+    transform(encoding.decoder);
 }
diff --git a/pkg/http/lib/src/multipart_file.dart b/pkg/http/lib/src/multipart_file.dart
index 29ef589..19c03bf 100644
--- a/pkg/http/lib/src/multipart_file.dart
+++ b/pkg/http/lib/src/multipart_file.dart
@@ -5,6 +5,7 @@
 library multipart_file;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
@@ -70,14 +71,14 @@
     contentType = contentType == null ? new ContentType("text", "plain")
                                       : contentType;
     var charset = contentType.charset;
-    var encoding = encodingForCharset(contentType.charset, Encoding.UTF_8);
+    var encoding = encodingForCharset(contentType.charset, UTF8);
     // Make a new contentType with ensured charset.
     contentType = new ContentType(contentType.primaryType,
                                   contentType.subType,
                                   charset: encoding.name,
                                   parameters: contentType.parameters);
 
-    return new MultipartFile.fromBytes(field, encodeString(value, encoding),
+    return new MultipartFile.fromBytes(field, encoding.encode(value),
         filename: filename,
         contentType: contentType);
   }
diff --git a/pkg/http/lib/src/request.dart b/pkg/http/lib/src/request.dart
index 9f024e6..8aacbe3 100644
--- a/pkg/http/lib/src/request.dart
+++ b/pkg/http/lib/src/request.dart
@@ -4,6 +4,7 @@
 
 library request;
 
+import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
 
@@ -36,7 +37,7 @@
   /// If the request has a `Content-Type` header and that header has a `charset`
   /// parameter, that parameter's value is used as the encoding. Otherwise, if
   /// [encoding] has been set manually, that encoding is used. If that hasn't
-  /// been set either, this defaults to [Encoding.UTF_8].
+  /// been set either, this defaults to [UTF8].
   ///
   /// If the `charset` parameter's value is not a known [Encoding], reading this
   /// will throw a [FormatException].
@@ -83,10 +84,10 @@
   /// header, one will be added with the type `text/plain`. Then the `charset`
   /// parameter of the `Content-Type` header (whether new or pre-existing) will
   /// be set to [encoding] if it wasn't already set.
-  String get body => decodeString(bodyBytes, encoding);
+  String get body => encoding.decode(bodyBytes);
 
   set body(String value) {
-    bodyBytes = encodeString(value, encoding);
+    bodyBytes = encoding.encode(value);
     var contentType = _contentType;
     if (contentType == null) {
       contentType = new ContentType("text", "plain", charset: encoding.name);
@@ -137,7 +138,7 @@
   /// Creates a new HTTP request.
   Request(String method, Uri url)
     : super(method, url),
-      _defaultEncoding = Encoding.UTF_8,
+      _defaultEncoding = UTF8,
       _bodyBytes = new Uint8List(0);
 
   /// Freezes all mutable fields and returns a single-subscription [ByteStream]
diff --git a/pkg/http/lib/src/response.dart b/pkg/http/lib/src/response.dart
index b7e0a48..435027d 100644
--- a/pkg/http/lib/src/response.dart
+++ b/pkg/http/lib/src/response.dart
@@ -5,6 +5,7 @@
 library response;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
 
@@ -21,10 +22,10 @@
   /// The body of the response as a string. This is converted from [bodyBytes]
   /// using the `charset` parameter of the `Content-Type` header field, if
   /// available. If it's unavailable or if the encoding name is unknown,
-  /// [Encoding.ISO_8859_1] is used by default, as per [RFC 2616][].
+  /// [LATIN1] is used by default, as per [RFC 2616][].
   ///
   /// [RFC 2616]: http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html
-  String get body => decodeString(bodyBytes, _encodingForHeaders(headers));
+  String get body => _encodingForHeaders(headers).decode(bodyBytes);
 
   /// Creates a new HTTP response with a string body.
   Response(
@@ -36,7 +37,7 @@
        bool persistentConnection: true,
        String reasonPhrase})
     : this.bytes(
-        encodeString(body, _encodingForHeaders(headers)),
+        _encodingForHeaders(headers).encode(body),
         statusCode,
         request: request,
         headers: headers,
@@ -80,7 +81,7 @@
 }
 
 /// Returns the encoding to use for a response with the given headers. This
-/// defaults to [Encoding.ISO_8859_1] if the headers don't specify a charset or
+/// defaults to [LATIN1] if the headers don't specify a charset or
 /// if that charset is unknown.
 Encoding _encodingForHeaders(Map<String, String> headers) =>
   encodingForCharset(_contentTypeForHeaders(headers).charset);
diff --git a/pkg/http/lib/src/utils.dart b/pkg/http/lib/src/utils.dart
index 420a3d5..cf2096d 100644
--- a/pkg/http/lib/src/utils.dart
+++ b/pkg/http/lib/src/utils.dart
@@ -5,9 +5,9 @@
 library utils;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
-import 'dart:utf';
 
 import 'byte_stream.dart';
 
@@ -66,9 +66,9 @@
 /// [charset] is null or if no [Encoding] was found that corresponds to
 /// [charset].
 Encoding encodingForCharset(
-    String charset, [Encoding fallback = Encoding.ISO_8859_1]) {
+    String charset, [Encoding fallback = LATIN1]) {
   if (charset == null) return fallback;
-  var encoding = Encoding.fromName(charset);
+  var encoding = Encoding.getByName(charset);
   return encoding == null ? fallback : encoding;
 }
 
@@ -77,23 +77,11 @@
 /// [FormatException] if no [Encoding] was found that corresponds to [charset].
 /// [charset] may not be null.
 Encoding requiredEncodingForCharset(String charset) {
-  var encoding = Encoding.fromName(charset);
+  var encoding = Encoding.getByName(charset);
   if (encoding != null) return encoding;
   throw new FormatException('Unsupported encoding "$charset".');
 }
 
-/// Converts [bytes] into a [String] according to [encoding].
-String decodeString(List<int> bytes, Encoding encoding) {
-  // TODO(nweiz): implement this once issue 6284 is fixed.
-  return decodeUtf8(bytes);
-}
-
-/// Converts [string] into a byte array according to [encoding].
-List<int> encodeString(String string, Encoding encoding) {
-  // TODO(nweiz): implement this once issue 6284 is fixed.
-  return encodeUtf8(string);
-}
-
 /// A regular expression that matches strings that are composed entirely of
 /// ASCII-compatible characters.
 final RegExp _ASCII_ONLY = new RegExp(r"^[\x00-\x7F]+$");
diff --git a/pkg/http/test/request_test.dart b/pkg/http/test/request_test.dart
index c9d82ce..4761dc0 100644
--- a/pkg/http/test/request_test.dart
+++ b/pkg/http/test/request_test.dart
@@ -4,6 +4,7 @@
 
 library request_test;
 
+import 'dart:convert';
 import 'dart:io';
 
 import 'package:http/http.dart' as http;
@@ -62,32 +63,32 @@
   group('#encoding', () {
     test('defaults to utf-8', () {
       var request = new http.Request('POST', dummyUrl);
-      expect(request.encoding.name, equals(Encoding.UTF_8.name));
+      expect(request.encoding.name, equals(UTF8.name));
     });
 
     test('can be set', () {
       var request = new http.Request('POST', dummyUrl);
-      request.encoding = Encoding.ISO_8859_1;
-      expect(request.encoding.name, equals(Encoding.ISO_8859_1.name));
+      request.encoding = LATIN1;
+      expect(request.encoding.name, equals(LATIN1.name));
     });
 
     test('is based on the content-type charset if it exists', () {
       var request = new http.Request('POST', dummyUrl);
       request.headers[HttpHeaders.CONTENT_TYPE] =
           'text/plain; charset=iso-8859-1';
-      expect(request.encoding.name, equals(Encoding.ISO_8859_1.name));
+      expect(request.encoding.name, equals(LATIN1.name));
     });
 
     test('remains the default if the content-type charset is set and unset',
         () {
       var request = new http.Request('POST', dummyUrl);
-      request.encoding = Encoding.ISO_8859_1;
+      request.encoding = LATIN1;
       request.headers[HttpHeaders.CONTENT_TYPE] =
           'text/plain; charset=utf-8';
-      expect(request.encoding.name, equals(Encoding.UTF_8.name));
+      expect(request.encoding.name, equals(UTF8.name));
 
       request.headers.remove(HttpHeaders.CONTENT_TYPE);
-      expect(request.encoding.name, equals(Encoding.ISO_8859_1.name));
+      expect(request.encoding.name, equals(LATIN1.name));
     });
 
     test('throws an error if the content-type charset is unknown', () {
@@ -240,7 +241,7 @@
 
     test('defaults to empty if only encoding is set', () {
       var request = new http.Request('POST', dummyUrl);
-      request.encoding = Encoding.ISO_8859_1;
+      request.encoding = LATIN1;
       expect(request.headers[HttpHeaders.CONTENT_TYPE], isNull);
     });
 
@@ -255,7 +256,7 @@
     test('is set to application/x-www-form-urlencoded with the given charset '
         'if bodyFields and encoding are set', () {
       var request = new http.Request('POST', dummyUrl);
-      request.encoding = Encoding.ISO_8859_1;
+      request.encoding = LATIN1;
       request.bodyFields = {'hello': 'world'};
       expect(request.headers[HttpHeaders.CONTENT_TYPE],
           equals('application/x-www-form-urlencoded; charset=iso-8859-1'));
@@ -264,7 +265,7 @@
     test('is set to text/plain and the given encoding if body and encoding are '
         'both set', () {
       var request = new http.Request('POST', dummyUrl);
-      request.encoding = Encoding.ISO_8859_1;
+      request.encoding = LATIN1;
       request.body = 'hello, world';
       expect(request.headers[HttpHeaders.CONTENT_TYPE],
           equals('text/plain; charset=iso-8859-1'));
@@ -281,7 +282,7 @@
     test('is modified to include the given encoding if encoding is set', () {
       var request = new http.Request('POST', dummyUrl);
       request.headers[HttpHeaders.CONTENT_TYPE] = 'application/json';
-      request.encoding = Encoding.ISO_8859_1;
+      request.encoding = LATIN1;
       expect(request.headers[HttpHeaders.CONTENT_TYPE],
           equals('application/json; charset=iso-8859-1'));
     });
@@ -290,7 +291,7 @@
       var request = new http.Request('POST', dummyUrl);
       request.headers[HttpHeaders.CONTENT_TYPE] =
           'application/json; charset=utf-8';
-      request.encoding = Encoding.ISO_8859_1;
+      request.encoding = LATIN1;
       expect(request.headers[HttpHeaders.CONTENT_TYPE],
           equals('application/json; charset=iso-8859-1'));
     });
@@ -350,8 +351,8 @@
       var request = new http.Request('POST', dummyUrl);
       request.finalize();
 
-      expect(request.encoding.name, equals(Encoding.UTF_8.name));
-      expect(() => request.encoding = Encoding.ASCII, throwsStateError);
+      expect(request.encoding.name, equals(UTF8.name));
+      expect(() => request.encoding = ASCII, throwsStateError);
     });
 
     test('freezes #bodyBytes', () {
diff --git a/pkg/http/test/utils.dart b/pkg/http/test/utils.dart
index 9c6e584..7b42bec 100644
--- a/pkg/http/test/utils.dart
+++ b/pkg/http/test/utils.dart
@@ -5,6 +5,7 @@
 library test_utils;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 import 'dart:json' as json;
 
@@ -62,7 +63,7 @@
         if (encodingName != null) {
           outputEncoding = requiredEncodingForCharset(encodingName);
         } else {
-          outputEncoding = Encoding.ASCII;
+          outputEncoding = ASCII;
         }
 
         response.headers.contentType =
@@ -76,7 +77,7 @@
         } else if (request.headers.contentType.charset != null) {
           var encoding = requiredEncodingForCharset(
               request.headers.contentType.charset);
-          requestBody = decodeString(requestBodyBytes, encoding);
+          requestBody = encoding.decode(requestBodyBytes);
         } else {
           requestBody = requestBodyBytes;
         }
diff --git a/pkg/http_server/lib/http_server.dart b/pkg/http_server/lib/http_server.dart
index 123ff7c..7176330 100644
--- a/pkg/http_server/lib/http_server.dart
+++ b/pkg/http_server/lib/http_server.dart
@@ -5,6 +5,7 @@
 library http_server;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 import 'dart:json' as JSON;
 
diff --git a/pkg/http_server/lib/src/http_body.dart b/pkg/http_server/lib/src/http_body.dart
index 422f9dc..f05d5b2 100644
--- a/pkg/http_server/lib/src/http_body.dart
+++ b/pkg/http_server/lib/src/http_body.dart
@@ -103,7 +103,7 @@
    * `multipart/form-data` content correctly. See the class comment
    * for more information on `multipart/form-data`.
    */
-  HttpBodyHandler({Encoding defaultEncoding: Encoding.UTF_8})
+  HttpBodyHandler({Encoding defaultEncoding: UTF8})
       : _transformer = new _HttpBodyHandlerTransformer(defaultEncoding);
 
   /**
@@ -114,7 +114,7 @@
    */
   static Future<HttpRequestBody> processRequest(
       HttpRequest request,
-      {Encoding defaultEncoding: Encoding.UTF_8}) {
+      {Encoding defaultEncoding: UTF8}) {
     return _HttpBodyHandler.processRequest(request, defaultEncoding);
   }
 
@@ -125,7 +125,7 @@
    */
   static Future<HttpClientResponseBody> processResponse(
       HttpClientResponse response,
-      {Encoding defaultEncoding: Encoding.UTF_8}) {
+      {Encoding defaultEncoding: UTF8}) {
     return _HttpBodyHandler.processResponse(response, defaultEncoding);
   }
 
diff --git a/pkg/http_server/lib/src/http_body_impl.dart b/pkg/http_server/lib/src/http_body_impl.dart
index 5d52874..c48db03 100644
--- a/pkg/http_server/lib/src/http_body_impl.dart
+++ b/pkg/http_server/lib/src/http_body_impl.dart
@@ -53,10 +53,10 @@
     Future<HttpBody> asText(Encoding defaultEncoding) {
       var encoding;
       var charset = contentType.charset;
-      if (charset != null) encoding = Encoding.fromName(charset);
+      if (charset != null) encoding = Encoding.getByName(charset);
       if (encoding == null) encoding = defaultEncoding;
       return stream
-          .transform(new StringDecoder(encoding))
+          .transform(encoding.decoder)
           .fold(new StringBuffer(), (buffer, data) => buffer..write(data))
           .then((buffer) => new _HttpBody(contentType,
                                           "text",
@@ -107,21 +107,21 @@
 
     switch (contentType.primaryType) {
       case "text":
-        return asText(Encoding.ASCII);
+        return asText(ASCII);
 
       case "application":
         switch (contentType.subType) {
           case "json":
-            return asText(Encoding.UTF_8)
+            return asText(UTF8)
                 .then((body) => new _HttpBody(contentType,
                                               "json",
                                               JSON.parse(body.body)));
 
           case "x-www-form-urlencoded":
-            return asText(Encoding.ASCII)
+            return asText(ASCII)
                 .then((body) {
                   var map = Uri.splitQueryString(body.body,
-                      decode: (s) => _decodeString(s, defaultEncoding));
+                      decode: (s) => defaultEncoding.decode(s));
                   var result = {};
                   for (var key in map.keys) {
                     result[key] = map[key];
@@ -150,24 +150,6 @@
 
     return asBinary();
   }
-
-  // Utility function to synchronously decode a list of bytes.
-  static String _decodeString(List<int> bytes,
-                              [Encoding encoding = Encoding.UTF_8]) {
-    if (bytes.length == 0) return "";
-    var string;
-    var error;
-    var controller = new StreamController(sync: true);
-    controller.stream
-      .transform(new StringDecoder(encoding))
-      .listen((data) => string = data,
-              onError: (e) => error = e);
-    controller.add(bytes);
-    controller.close();
-    if (error != null) throw error;
-    assert(string != null);
-    return string;
-  }
 }
 
 class _HttpBodyFileUpload implements HttpBodyFileUpload {
diff --git a/pkg/http_server/lib/src/http_multipart_form_data_impl.dart b/pkg/http_server/lib/src/http_multipart_form_data_impl.dart
index 8b313aa..7956c0f 100644
--- a/pkg/http_server/lib/src/http_multipart_form_data_impl.dart
+++ b/pkg/http_server/lib/src/http_multipart_form_data_impl.dart
@@ -34,11 +34,11 @@
       StringBuffer buffer = new StringBuffer();
       Encoding encoding;
       if (contentType != null) {
-        encoding = Encoding.fromName(contentType.charset);
+        encoding = Encoding.getByName(contentType.charset);
       }
-      if (encoding == null) encoding = Encoding.ISO_8859_1;
+      if (encoding == null) encoding = LATIN1;
       _stream = _stream
-          .transform(new StringDecoder(encoding))
+          .transform(encoding.decoder)
           .expand((data) {
             buffer.write(data);
             var out = _decodeHttpEntityString(buffer.toString());
diff --git a/pkg/http_server/test/http_body_test.dart b/pkg/http_server/test/http_body_test.dart
index 725480b..7f510e7 100644
--- a/pkg/http_server/test/http_body_test.dart
+++ b/pkg/http_server/test/http_body_test.dart
@@ -3,7 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:io';
-import 'dart:utf';
+import 'dart:convert';
 
 import 'package:http_server/http_server.dart';
 import 'package:unittest/unittest.dart';
@@ -66,11 +66,8 @@
        "body",
        "text");
   test("text/plain; charset=utf-8", [42], "*", "text");
-  test("text/plain; charset=us-ascii", [142], "?", "text");
-  test("text/plain; charset=utf-8",
-       [142],
-       new String.fromCharCodes([UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]),
-       "text");
+  test("text/plain; charset=us-ascii", [142], null, "text", true);
+  test("text/plain; charset=utf-8", [142], null, "text", true);
 
   test("application/json",
        '{"val": 5}'.codeUnits,
@@ -89,7 +86,7 @@
             dynamic expectedBody,
             String type,
             {bool shouldFail: false,
-             Encoding defaultEncoding: Encoding.UTF_8}) {
+             Encoding defaultEncoding: UTF8}) {
     HttpServer.bind("127.0.0.1", 0).then((server) {
       server.transform(new HttpBodyHandler(defaultEncoding: defaultEncoding))
           .listen((body) {
@@ -169,11 +166,8 @@
        "body",
        "text");
   test("text/plain; charset=utf-8", [42], "*", "text");
-  test("text/plain; charset=us-ascii", [142], "?", "text");
-  test("text/plain; charset=utf-8",
-       [142],
-       new String.fromCharCodes([UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]),
-       "text");
+  test("text/plain; charset=us-ascii", [142], null, "text", shouldFail: true);
+  test("text/plain; charset=utf-8", [142], null, "text", shouldFail: true);
 
   test("application/json",
        '{"val": 5}'.codeUnits,
@@ -250,23 +244,27 @@
 
   test('application/x-www-form-urlencoded',
        'a=%F8+%26%23548%3B'.codeUnits,
-       { 'a' : '\u{FFFD} &#548;' },
-       "form");
+       null,
+       "form",
+       shouldFail: true);
 
   test('application/x-www-form-urlencoded',
        'a=%C0%A0'.codeUnits,
-       { 'a' : '\u{FFFD}' },
-       "form");
+       null,
+       "form",
+       shouldFail: true);
 
   test('application/x-www-form-urlencoded',
        'a=x%A0x'.codeUnits,
-       { 'a' : 'x\u{FFFD}x' },
-       "form");
+       null,
+       "form",
+       shouldFail: true);
 
   test('application/x-www-form-urlencoded',
        'a=x%C0x'.codeUnits,
-       { 'a' : 'x\u{FFFD}x' },
-       "form");
+       null,
+       "form",
+       shouldFail: true);
 
   test('application/x-www-form-urlencoded',
        'a=%C3%B8+%C8%A4'.codeUnits,
@@ -277,31 +275,31 @@
        'a=%F8+%26%23548%3B'.codeUnits,
        { 'a' : 'ø &#548;' },
        "form",
-       defaultEncoding: Encoding.ISO_8859_1);
+       defaultEncoding: LATIN1);
 
   test('application/x-www-form-urlencoded',
        'name=%26'.codeUnits,
        { 'name' : '&' },
        "form",
-       defaultEncoding: Encoding.ISO_8859_1);
+       defaultEncoding: LATIN1);
 
   test('application/x-www-form-urlencoded',
        'name=%F8%26'.codeUnits,
        { 'name' : 'ø&' },
        "form",
-       defaultEncoding: Encoding.ISO_8859_1);
+       defaultEncoding: LATIN1);
 
   test('application/x-www-form-urlencoded',
        'name=%26%3B'.codeUnits,
        { 'name' : '&;' },
        "form",
-       defaultEncoding: Encoding.ISO_8859_1);
+       defaultEncoding: LATIN1);
 
   test('application/x-www-form-urlencoded',
        'name=%26%23548%3B%26%23548%3B'.codeUnits,
        { 'name' : '&#548;&#548;' },
        "form",
-       defaultEncoding: Encoding.ISO_8859_1);
+       defaultEncoding: LATIN1);
 
   test('application/x-www-form-urlencoded',
        'name=%26'.codeUnits,
diff --git a/pkg/http_server/test/utils.dart b/pkg/http_server/test/utils.dart
index 6a46696..c9e39c7 100644
--- a/pkg/http_server/test/utils.dart
+++ b/pkg/http_server/test/utils.dart
@@ -5,6 +5,7 @@
 library utils;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 import "package:path/path.dart";
 
@@ -49,7 +50,7 @@
 Future<String> getAsString(int port, String path) {
   return new HttpClient().get('localhost', port, path)
       .then((request) => request.close())
-      .then((response) => StringDecoder.decode(response));
+      .then((response) => UTF8.decodeStream(response));
 }
 
 
diff --git a/pkg/scheduled_test/lib/scheduled_process.dart b/pkg/scheduled_test/lib/scheduled_process.dart
index 27ebc17..4768c68 100644
--- a/pkg/scheduled_test/lib/scheduled_process.dart
+++ b/pkg/scheduled_test/lib/scheduled_process.dart
@@ -82,7 +82,7 @@
   /// may be a [List] containing a mix of strings and [Future]s.
   ScheduledProcess.start(executable, arguments,
       {workingDirectory, environment, String description,
-       Encoding encoding: Encoding.UTF_8})
+       Encoding encoding: UTF8})
       : _encoding = encoding,
         _explicitDescription = description != null,
         _description = description {
@@ -152,7 +152,7 @@
                              arguments,
                              workingDirectory: workingDirectory,
                              environment: environment).then((process) {
-          process.stdin.encoding = Encoding.UTF_8;
+          process.stdin.encoding = UTF8;
           return process;
         });
       });
@@ -203,7 +203,7 @@
       currentSchedule.heartbeat();
       return chunk;
     })
-        .transform(new StringDecoder(_encoding))
+        .transform(_encoding.decoder)
         .transform(new LineSplitter()));
   }
 
diff --git a/pkg/scheduled_test/test/scheduled_process_test.dart b/pkg/scheduled_test/test/scheduled_process_test.dart
index 33cfa7c..5aaae60 100644
--- a/pkg/scheduled_test/test/scheduled_process_test.dart
+++ b/pkg/scheduled_test/test/scheduled_process_test.dart
@@ -372,7 +372,7 @@
           import 'dart:io';
 
           var stdinLines = stdin
-              .transform(new StringDecoder())
+              .transform(UTF8.decoder)
               .transform(new LineSplitter());
 
           void main() {
diff --git a/runtime/bin/process_patch.dart b/runtime/bin/process_patch.dart
index 62489ca..441e75b 100644
--- a/runtime/bin/process_patch.dart
+++ b/runtime/bin/process_patch.dart
@@ -38,8 +38,8 @@
        Map<String, String> environment,
        bool includeParentEnvironment: true,
        bool runInShell: false,
-       Encoding stdoutEncoding: Encoding.SYSTEM,
-       Encoding stderrEncoding: Encoding.SYSTEM}) {
+       Encoding stdoutEncoding: SYSTEM_ENCODING,
+       Encoding stderrEncoding: SYSTEM_ENCODING}) {
     return _runNonInteractiveProcess(executable,
                                      arguments,
                                      workingDirectory,
@@ -57,8 +57,8 @@
        Map<String, String> environment,
        bool includeParentEnvironment: true,
        bool runInShell: false,
-       Encoding stdoutEncoding: Encoding.SYSTEM,
-       Encoding stderrEncoding: Encoding.SYSTEM}) {
+       Encoding stdoutEncoding: SYSTEM_ENCODING,
+       Encoding stderrEncoding: SYSTEM_ENCODING}) {
     return _runNonInteractiveProcessSync(executable,
                                          arguments,
                                          workingDirectory,
@@ -324,7 +324,7 @@
 
     getOutput(output, encoding) {
       if (stderrEncoding == null) return output;
-      return _decodeString(output, encoding);
+      return encoding.decode(output);
     }
 
     return new _ProcessResult(
@@ -424,7 +424,7 @@
             .then((builder) => builder.takeBytes());
       } else {
         return stream
-            .transform(new StringDecoder(encoding))
+            .transform(encoding.decoder)
             .fold(
                 new StringBuffer(),
                 (buf, data) {
diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
index 6259451..a57a46a 100644
--- a/runtime/vm/exceptions.cc
+++ b/runtime/vm/exceptions.cc
@@ -412,21 +412,13 @@
     // TODO(5411263): At some point we can optimize by figuring out if a
     // stack trace is needed based on whether the catch code specifies a
     // stack trace object or there is a rethrow in the catch clause.
-    if (pc_offset_array.Length() != 0) {
-      if (existing_stacktrace.IsNull()) {
+    if (existing_stacktrace.IsNull()) {
         stacktrace = Stacktrace::New(func_array, code_array, pc_offset_array);
-      } else {
-        stacktrace ^= existing_stacktrace.raw();
-        stacktrace.Append(func_array, code_array, pc_offset_array);
-        // Since we are re throwing and appending to the existing stack trace
-        // we clear out the catch trace collected in the existing stack trace
-        // as that trace will not be valid anymore.
-        stacktrace.SetCatchStacktrace(Object::empty_array(),
-                                      Object::empty_array(),
-                                      Object::empty_array());
-      }
     } else {
       stacktrace ^= existing_stacktrace.raw();
+      if (pc_offset_array.Length() != 0) {
+        stacktrace.Append(func_array, code_array, pc_offset_array);
+      }
       // Since we are re throwing and appending to the existing stack trace
       // we clear out the catch trace collected in the existing stack trace
       // as that trace will not be valid anymore.
diff --git a/runtime/vm/flow_graph_type_propagator.cc b/runtime/vm/flow_graph_type_propagator.cc
index 2ea65ba..ba39000 100644
--- a/runtime/vm/flow_graph_type_propagator.cc
+++ b/runtime/vm/flow_graph_type_propagator.cc
@@ -491,8 +491,7 @@
 intptr_t CompileType::ToNullableCid() {
   if (cid_ == kIllegalCid) {
     if (type_ == NULL) {
-      // Type propagation is turned off.
-      ASSERT(!FLAG_propagate_types);
+      // Type propagation is turned off or has not yet run.
       return kDynamicCid;
     } else if (type_->IsMalformed()) {
       cid_ = kDynamicCid;
diff --git a/runtime/vm/intrinsifier_arm.cc b/runtime/vm/intrinsifier_arm.cc
index 312912e..1a528f0 100644
--- a/runtime/vm/intrinsifier_arm.cc
+++ b/runtime/vm/intrinsifier_arm.cc
@@ -1480,7 +1480,7 @@
   __ LoadObject(R0, Bool::True(), EQ);
   __ LoadObject(R0, Bool::False(), NE);
   __ Ret();
-  return true;
+  return false;
 }
 
 
diff --git a/runtime/vm/intrinsifier_ia32.cc b/runtime/vm/intrinsifier_ia32.cc
index 07932b0..aac288d 100644
--- a/runtime/vm/intrinsifier_ia32.cc
+++ b/runtime/vm/intrinsifier_ia32.cc
@@ -1550,7 +1550,7 @@
   __ Bind(&is_true);
   __ LoadObject(EAX, Bool::True());
   __ ret();
-  return true;
+  return false;
 }
 
 
diff --git a/runtime/vm/intrinsifier_mips.cc b/runtime/vm/intrinsifier_mips.cc
index 517e89b..81dacc7 100644
--- a/runtime/vm/intrinsifier_mips.cc
+++ b/runtime/vm/intrinsifier_mips.cc
@@ -1558,7 +1558,7 @@
   __ Bind(&is_true);
   __ LoadObject(V0, Bool::True());
   __ Ret();
-  return true;
+  return false;
 }
 
 
diff --git a/runtime/vm/intrinsifier_x64.cc b/runtime/vm/intrinsifier_x64.cc
index aa3ebff..f6d70b6 100644
--- a/runtime/vm/intrinsifier_x64.cc
+++ b/runtime/vm/intrinsifier_x64.cc
@@ -1466,7 +1466,7 @@
   __ Bind(&is_true);
   __ LoadObject(RAX, Bool::True());
   __ ret();
-  return true;
+  return false;
 }
 
 
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index 9815cea..cdbb608 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -762,12 +762,27 @@
 }
 
 
+static bool IsInvisible(const Function& func) {
+  if (!Library::IsPrivate(String::Handle(func.name()))) return false;
+  // Check for private function in the core libraries.
+  const Class& cls = Class::Handle(func.Owner());
+  const Library& library = Library::Handle(cls.library());
+  if (library.raw() == Library::CoreLibrary()) return true;
+  if (library.raw() == Library::CollectionLibrary()) return true;
+  if (library.raw() == Library::TypedDataLibrary()) return true;
+  if (library.raw() == Library::MathLibrary()) return true;
+  return false;
+}
+
+
 void Parser::ParseFunction(ParsedFunction* parsed_function) {
   TimerScope timer(FLAG_compiler_stats, &CompilerStats::parser_timer);
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate->long_jump_base()->IsSafeToJump());
   ASSERT(parsed_function != NULL);
   const Function& func = parsed_function->function();
+  // Mark private core library functions as invisible by default.
+  if (IsInvisible(func)) func.set_is_visible(false);
   const Script& script = Script::Handle(isolate, func.script());
   Parser parser(script, parsed_function, func.token_pos());
   SequenceNode* node_sequence = NULL;
diff --git a/sdk/lib/_internal/lib/io_patch.dart b/sdk/lib/_internal/lib/io_patch.dart
index 80725b8..0bd68ac 100644
--- a/sdk/lib/_internal/lib/io_patch.dart
+++ b/sdk/lib/_internal/lib/io_patch.dart
@@ -208,8 +208,8 @@
        Map<String, String> environment,
        bool includeParentEnvironment: true,
        bool runInShell: false,
-       Encoding stdoutEncoding: Encoding.SYSTEM,
-       Encoding stderrEncoding: Encoding.SYSTEM}) {
+       Encoding stdoutEncoding: SYSTEM_ENCODING,
+       Encoding stderrEncoding: SYSTEM_ENCODING}) {
     throw new UnsupportedError("Process.run");
   }
 
@@ -220,8 +220,8 @@
        Map<String, String> environment,
        bool includeParentEnvironment: true,
        bool runInShell: false,
-       Encoding stdoutEncoding: Encoding.SYSTEM,
-       Encoding stderrEncoding: Encoding.SYSTEM}) {
+       Encoding stdoutEncoding: SYSTEM_ENCODING,
+       Encoding stderrEncoding: SYSTEM_ENCODING}) {
     throw new UnsupportedError("Process.runSync");
   }
 }
diff --git a/sdk/lib/_internal/pub/lib/src/io.dart b/sdk/lib/_internal/pub/lib/src/io.dart
index 5847fed..0bd5c14 100644
--- a/sdk/lib/_internal/pub/lib/src/io.dart
+++ b/sdk/lib/_internal/pub/lib/src/io.dart
@@ -7,6 +7,7 @@
 
 import 'dart:async';
 import 'dart:collection';
+import 'dart:convert';
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
@@ -136,7 +137,7 @@
 
 /// Reads the contents of the text file [file].
 String readTextFile(String file) =>
-    new File(file).readAsStringSync(encoding: Encoding.UTF_8);
+    new File(file).readAsStringSync(encoding: UTF8);
 
 /// Reads the contents of the binary file [file].
 List<int> readBinaryFile(String file) {
diff --git a/sdk/lib/_internal/pub/lib/src/safe_http_server.dart b/sdk/lib/_internal/pub/lib/src/safe_http_server.dart
index 634a76f..f5f57cf 100644
--- a/sdk/lib/_internal/pub/lib/src/safe_http_server.dart
+++ b/sdk/lib/_internal/pub/lib/src/safe_http_server.dart
@@ -5,6 +5,7 @@
 library pub.safe_http_server;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 
 // TODO(nweiz): remove this when issue 9140 is fixed.
diff --git a/sdk/lib/_internal/pub/test/test_pub.dart b/sdk/lib/_internal/pub/test/test_pub.dart
index f1358a9..81e74e8 100644
--- a/sdk/lib/_internal/pub/test/test_pub.dart
+++ b/sdk/lib/_internal/pub/test/test_pub.dart
@@ -9,6 +9,7 @@
 library test_pub;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 import 'dart:json' as json;
 import 'dart:math';
@@ -501,7 +502,7 @@
 
   PubProcess.start(executable, arguments,
       {workingDirectory, environment, String description,
-       Encoding encoding: Encoding.UTF_8})
+       Encoding encoding: UTF8})
     : super.start(executable, arguments,
         workingDirectory: workingDirectory,
         environment: environment,
diff --git a/sdk/lib/convert/ascii.dart b/sdk/lib/convert/ascii.dart
index bea9680..56d6c89 100644
--- a/sdk/lib/convert/ascii.dart
+++ b/sdk/lib/convert/ascii.dart
@@ -24,7 +24,7 @@
  * An [AsciiCodec] allows encoding strings as ASCII bytes
  * and decoding ASCII bytes to strings.
  */
-class AsciiCodec extends _Encoding {
+class AsciiCodec extends Encoding {
   final bool _allowInvalid;
   /**
    * Instantiates a new [AsciiCodec].
@@ -39,6 +39,8 @@
    */
   const AsciiCodec({bool allowInvalid: false}) : _allowInvalid = allowInvalid;
 
+  String get name => "us-ascii";
+
   /**
    * Decodes the ASCII [bytes] (a list of unsigned 7-bit integers) to the
    * corresponding string.
diff --git a/sdk/lib/convert/encoding.dart b/sdk/lib/convert/encoding.dart
index 0f6126c..cc67f6f 100644
--- a/sdk/lib/convert/encoding.dart
+++ b/sdk/lib/convert/encoding.dart
@@ -7,13 +7,70 @@
 /**
  * Open-ended Encoding enum.
  */
-// TODO(floitsch): dart:io already has an Encoding class. If we can't
-// consolitate them, we need to remove `Encoding` here.
-abstract class _Encoding extends Codec<String, List<int>> {
-  const _Encoding();
+abstract class Encoding extends Codec<String, List<int>> {
+  const Encoding();
 
-  // TODO(floitsch): should we introduce a StringToByteEncoder and
-  // a ByteToStringDecoder so that we have better typing?
+  Future<String> decodeStream(Stream<List<int>> byteStream) {
+    return byteStream
+      .transform(decoder)
+      .fold(new StringBuffer(), (buffer, string) => buffer..write(string))
+      .then((buffer) => buffer.toString());
+  }
+
+  /**
+   * Name of the encoding.
+   *
+   * If the encoding is standardized, this is the lower-case version of one of
+   * the IANA official names for the character set (see
+   * http://www.iana.org/assignments/character-sets/character-sets.xml)
+   */
+  String get name;
+
+  // All aliases (in lowercase) of supported encoding from
+  // http://www.iana.org/assignments/character-sets/character-sets.xml.
+  static Map<String, Encoding> _nameToEncoding = <String, Encoding> {
+    // ISO_8859-1:1987.
+    "iso_8859-1:1987": LATIN1,
+    "iso-ir-100": LATIN1,
+    "iso_8859-1": LATIN1,
+    "iso-8859-1": LATIN1,
+    "latin1": LATIN1,
+    "l1": LATIN1,
+    "ibm819": LATIN1,
+    "cp819": LATIN1,
+    "csisolatin1": LATIN1,
+
+    // US-ASCII.
+    "iso-ir-6": ASCII,
+    "ansi_x3.4-1968": ASCII,
+    "ansi_x3.4-1986": ASCII,
+    "iso_646.irv:1991": ASCII,
+    "iso646-us": ASCII,
+    "us-ascii": ASCII,
+    "us": ASCII,
+    "ibm367": ASCII,
+    "cp367": ASCII,
+    "csascii": ASCII,
+    "ascii": ASCII,  // This is not in the IANA official names.
+
+    // UTF-8.
+    "csutf8": UTF8,
+    "utf-8": UTF8
+  };
+
+  /**
+  * Gets an [Encoding] object from the name of the character set
+  * name. The names used are the IANA official names for the
+  * character set (see
+  * http://www.iana.org/assignments/character-sets/character-sets.xml).
+  *
+  * The [name] passed is case insensitive.
+  *
+  * If character set is not supported [:null:] is returned.
+  */
+  static Encoding getByName(String name) {
+      if (name == null) return null;
+      name = name.toLowerCase();
+      return _nameToEncoding[name];
+  }
 }
-
-// TODO(floitsch): add other encodings, like ASCII and ISO_8859_1.
diff --git a/sdk/lib/convert/latin1.dart b/sdk/lib/convert/latin1.dart
index 3e9232f..2fca67c 100644
--- a/sdk/lib/convert/latin1.dart
+++ b/sdk/lib/convert/latin1.dart
@@ -24,7 +24,7 @@
  * A [LatinCodec] encodes strings to ISO Latin-1 (aka ISO-8859-1) bytes
  * and decodes Latin-1 bytes to strings.
  */
-class Latin1Codec extends _Encoding {
+class Latin1Codec extends Encoding {
   final bool _allowInvalid;
   /**
    * Instantiates a new [Latin1Codec].
@@ -38,6 +38,8 @@
    */
   const Latin1Codec({bool allowInvalid: false}) : _allowInvalid = allowInvalid;
 
+  String get name => "iso-8859-1";
+
   /**
    * Decodes the Latin-1 [bytes] (a list of unsigned 8-bit integers) to the
    * corresponding string.
diff --git a/sdk/lib/convert/utf.dart b/sdk/lib/convert/utf.dart
index 37f2335..6abaa05 100644
--- a/sdk/lib/convert/utf.dart
+++ b/sdk/lib/convert/utf.dart
@@ -4,6 +4,9 @@
 
 part of dart.convert;
 
+/** The Unicode Replacement character `U+FFFD` (�). */
+const UNICODE_REPLACEMENT_CHARACTER_RUNE = 0xFFFD;
+
 /**
  * An instance of the default implementation of the [Utf8Codec].
  *
@@ -22,7 +25,7 @@
  * A [Utf8Codec] encodes strings to utf-8 code units (bytes) and decodes
  * UTF-8 code units to strings.
  */
-class Utf8Codec extends _Encoding {
+class Utf8Codec extends Encoding {
   final bool _allowMalformed;
 
   /**
@@ -39,6 +42,8 @@
   const Utf8Codec({ bool allowMalformed: false })
       : _allowMalformed = allowMalformed;
 
+  String get name => "utf-8";
+
   /**
    * Decodes the UTF-8 [codeUnits] (a list of unsigned 8-bit integers) to the
    * corresponding string.
@@ -66,6 +71,9 @@
  * unsigned 8-bit integers).
  */
 class Utf8Encoder extends Converter<String, List<int>> {
+
+  const Utf8Encoder();
+
   /**
    * Converts [string] to its UTF-8 code units (a list of
    * unsigned 8-bit integers).
@@ -289,7 +297,7 @@
    * sequences with the Unicode Replacement character `U+FFFD` (�). Otherwise
    * it throws a [FormatException].
    */
-  Utf8Decoder({ bool allowMalformed: false })
+  const Utf8Decoder({ bool allowMalformed: false })
       : this._allowMalformed = allowMalformed;
 
   /**
diff --git a/sdk/lib/io/file.dart b/sdk/lib/io/file.dart
index 5cbff1c..ffcadc7 100644
--- a/sdk/lib/io/file.dart
+++ b/sdk/lib/io/file.dart
@@ -204,7 +204,7 @@
    *  [IOSink] has been created.
    */
   IOSink openWrite({FileMode mode: FileMode.WRITE,
-                    Encoding encoding: Encoding.UTF_8});
+                    Encoding encoding: UTF8});
 
   /**
    * Read the entire file contents as a list of bytes. Returns a
@@ -227,7 +227,7 @@
    * Returns a [:Future<String>:] that completes with the string once
    * the file contents has been read.
    */
-  Future<String> readAsString({Encoding encoding: Encoding.UTF_8});
+  Future<String> readAsString({Encoding encoding: UTF8});
 
   /**
    * Synchronously read the entire file contents as a string using the
@@ -235,7 +235,7 @@
    *
    * Throws a [FileException] if the operation fails.
    */
-  String readAsStringSync({Encoding encoding: Encoding.UTF_8});
+  String readAsStringSync({Encoding encoding: UTF8});
 
   /**
    * Read the entire file contents as lines of text using the given
@@ -244,7 +244,7 @@
    * Returns a [:Future<List<String>>:] that completes with the lines
    * once the file contents has been read.
    */
-  Future<List<String>> readAsLines({Encoding encoding: Encoding.UTF_8});
+  Future<List<String>> readAsLines({Encoding encoding: UTF8});
 
   /**
    * Synchronously read the entire file contents as lines of text
@@ -252,7 +252,7 @@
    *
    * Throws a [FileException] if the operation fails.
    */
-  List<String> readAsLinesSync({Encoding encoding: Encoding.UTF_8});
+  List<String> readAsLinesSync({Encoding encoding: UTF8});
 
   /**
    * Write a list of bytes to a file.
@@ -293,7 +293,7 @@
    */
   Future<File> writeAsString(String contents,
                              {FileMode mode: FileMode.WRITE,
-                              Encoding encoding: Encoding.UTF_8});
+                              Encoding encoding: UTF8});
 
   /**
    * Synchronously write a string to a file.
@@ -310,7 +310,7 @@
    */
   void writeAsStringSync(String contents,
                          {FileMode mode: FileMode.WRITE,
-                          Encoding encoding: Encoding.UTF_8});
+                          Encoding encoding: UTF8});
 
   /**
    * Get the path of the file.
@@ -428,7 +428,7 @@
    * RandomAccessFile when the write completes.
    */
   Future<RandomAccessFile> writeString(String string,
-                                       {Encoding encoding: Encoding.UTF_8});
+                                       {Encoding encoding: UTF8});
 
   /**
    * Synchronously writes a single string to the file using the given
@@ -437,7 +437,7 @@
    * Throws a [FileException] if the operation fails.
    */
   void writeStringSync(String string,
-                       {Encoding encoding: Encoding.UTF_8});
+                       {Encoding encoding: UTF8});
 
   /**
    * Gets the current byte position in the file. Returns a
diff --git a/sdk/lib/io/file_impl.dart b/sdk/lib/io/file_impl.dart
index 1dd2b47..3ce6ee1 100644
--- a/sdk/lib/io/file_impl.dart
+++ b/sdk/lib/io/file_impl.dart
@@ -466,7 +466,7 @@
   }
 
   IOSink openWrite({FileMode mode: FileMode.WRITE,
-                    Encoding encoding: Encoding.UTF_8}) {
+                    Encoding encoding: UTF8}) {
     if (mode != FileMode.WRITE &&
         mode != FileMode.APPEND) {
       throw new ArgumentError(
@@ -503,16 +503,16 @@
     return builder.takeBytes();
   }
 
-  Future<String> readAsString({Encoding encoding: Encoding.UTF_8}) {
+  Future<String> readAsString({Encoding encoding: UTF8}) {
     _ensureFileService();
     return readAsBytes().then((bytes) {
-      return _decodeString(bytes, encoding);
+      return encoding.decode(bytes);
     });
   }
 
-  String readAsStringSync({Encoding encoding: Encoding.UTF_8}) {
+  String readAsStringSync({Encoding encoding: UTF8}) {
     List<int> bytes = readAsBytesSync();
-    return _decodeString(bytes, encoding);
+    return encoding.decode(bytes);
   }
 
   static List<String> _decodeLines(List<int> bytes, Encoding encoding) {
@@ -520,7 +520,7 @@
     var list = [];
     var controller = new StreamController(sync: true);
     controller.stream
-        .transform(new StringDecoder(encoding))
+        .transform(encoding.decoder)
         .transform(new LineSplitter())
         .listen((line) => list.add(line));
     controller.add(bytes);
@@ -528,14 +528,14 @@
     return list;
   }
 
-  Future<List<String>> readAsLines({Encoding encoding: Encoding.UTF_8}) {
+  Future<List<String>> readAsLines({Encoding encoding: UTF8}) {
     _ensureFileService();
     return readAsBytes().then((bytes) {
       return _decodeLines(bytes, encoding);
     });
   }
 
-  List<String> readAsLinesSync({Encoding encoding: Encoding.UTF_8}) {
+  List<String> readAsLinesSync({Encoding encoding: UTF8}) {
     return _decodeLines(readAsBytesSync(), encoding);
   }
 
@@ -559,9 +559,9 @@
 
   Future<File> writeAsString(String contents,
                              {FileMode mode: FileMode.WRITE,
-                              Encoding encoding: Encoding.UTF_8}) {
+                              Encoding encoding: UTF8}) {
     try {
-      return writeAsBytes(_encodeString(contents, encoding), mode: mode);
+      return writeAsBytes(encoding.encode(contents), mode: mode);
     } catch (e) {
       return new Future.error(e);
     }
@@ -569,8 +569,8 @@
 
   void writeAsStringSync(String contents,
                          {FileMode mode: FileMode.WRITE,
-                          Encoding encoding: Encoding.UTF_8}) {
-    writeAsBytesSync(_encodeString(contents, encoding), mode: mode);
+                          Encoding encoding: UTF8}) {
+    writeAsBytesSync(encoding.encode(contents), mode: mode);
   }
 
   String toString() => "File: '$path'";
@@ -824,19 +824,19 @@
   }
 
   Future<RandomAccessFile> writeString(String string,
-                                       {Encoding encoding: Encoding.UTF_8}) {
+                                       {Encoding encoding: UTF8}) {
     if (encoding is! Encoding) {
       throw new ArgumentError(encoding);
     }
-    var data = _encodeString(string, encoding);
+    var data = encoding.encode(string);
     return writeFrom(data, 0, data.length);
   }
 
-  void writeStringSync(String string, {Encoding encoding: Encoding.UTF_8}) {
+  void writeStringSync(String string, {Encoding encoding: UTF8}) {
     if (encoding is! Encoding) {
       throw new ArgumentError(encoding);
     }
-    var data = _encodeString(string, encoding);
+    var data = encoding.encode(string);
     writeFromSync(data, 0, data.length);
   }
 
diff --git a/sdk/lib/io/http_impl.dart b/sdk/lib/io/http_impl.dart
index f7b9041..a7cac9f 100644
--- a/sdk/lib/io/http_impl.dart
+++ b/sdk/lib/io/http_impl.dart
@@ -410,7 +410,7 @@
                        String protocolVersion,
                        _HttpOutgoing outgoing)
       : _outgoing = outgoing,
-        _headersSink = new IOSink(outgoing, encoding: Encoding.ASCII),
+        _headersSink = new IOSink(outgoing, encoding: ASCII),
         headers = new _HttpHeaders(protocolVersion) {
     _dataSink = new IOSink(new _HttpOutboundConsumer(this));
   }
@@ -432,7 +432,7 @@
     } else {
       charset = "iso-8859-1";
     }
-    return Encoding.fromName(charset);
+    return Encoding.getByName(charset);
   }
 
   void set encoding(Encoding value) {
@@ -1222,7 +1222,7 @@
       // If the proxy configuration contains user information use that
       // for proxy basic authorization.
       String auth = _CryptoUtils.bytesToBase64(
-          _encodeString("${proxy.username}:${proxy.password}"));
+          UTF8.encode("${proxy.username}:${proxy.password}"));
       request.headers.set(HttpHeaders.PROXY_AUTHORIZATION, "Basic $auth");
     } else if (!proxy.isDirect && _httpClient._proxyCredentials.length > 0) {
       proxyCreds = _httpClient._findProxyCredentials(proxy);
@@ -1234,7 +1234,7 @@
       // If the URL contains user information use that for basic
       // authorization.
       String auth =
-          _CryptoUtils.bytesToBase64(_encodeString(uri.userInfo));
+          _CryptoUtils.bytesToBase64(UTF8.encode(uri.userInfo));
       request.headers.set(HttpHeaders.AUTHORIZATION, "Basic $auth");
     } else {
       // Look for credentials.
@@ -1345,7 +1345,7 @@
       // If the proxy configuration contains user information use that
       // for proxy basic authorization.
       String auth = _CryptoUtils.bytesToBase64(
-          _encodeString("${proxy.username}:${proxy.password}"));
+          UTF8.encode("${proxy.username}:${proxy.password}"));
       request.headers.set(HttpHeaders.PROXY_AUTHORIZATION, "Basic $auth");
     }
     return request.close()
@@ -2270,11 +2270,11 @@
       // now always use UTF-8 encoding.
       _HttpClientDigestCredentials creds = credentials;
       var hasher = new _MD5();
-      hasher.add(_encodeString(creds.username));
+      hasher.add(UTF8.encode(creds.username));
       hasher.add([_CharCode.COLON]);
       hasher.add(realm.codeUnits);
       hasher.add([_CharCode.COLON]);
-      hasher.add(_encodeString(creds.password));
+      hasher.add(UTF8.encode(creds.password));
       ha1 = _CryptoUtils.bytesToHex(hasher.close());
     }
   }
@@ -2363,7 +2363,7 @@
     // http://tools.ietf.org/html/draft-reschke-basicauth-enc-06. For
     // now always use UTF-8 encoding.
     String auth =
-        _CryptoUtils.bytesToBase64(_encodeString("$username:$password"));
+        _CryptoUtils.bytesToBase64(UTF8.encode("$username:$password"));
     return "Basic $auth";
   }
 
diff --git a/sdk/lib/io/io.dart b/sdk/lib/io/io.dart
index 37a65c1..e390d31 100644
--- a/sdk/lib/io/io.dart
+++ b/sdk/lib/io/io.dart
@@ -4,7 +4,7 @@
 
 /**
  * File, socket, HTTP, and other I/O support for server applications.
- * 
+ *
  * The IO library is used for Dart server applications,
  * which run on a stand-alone Dart VM from the command line.
  * *This library does not work in browser based applications.*
@@ -23,7 +23,6 @@
 import 'dart:isolate';
 import 'dart:json' as JSON;
 import 'dart:math';
-import 'dart:utf';
 import 'dart:typed_data';
 
 part 'bytes_builder.dart';
diff --git a/sdk/lib/io/io_sink.dart b/sdk/lib/io/io_sink.dart
index b954a86..ac4ce0a 100644
--- a/sdk/lib/io/io_sink.dart
+++ b/sdk/lib/io/io_sink.dart
@@ -19,7 +19,7 @@
  */
 abstract class IOSink implements StreamSink<List<int>>, StringSink {
   factory IOSink(StreamConsumer<List<int>> target,
-                 {Encoding encoding: Encoding.UTF_8})
+                 {Encoding encoding: UTF8})
       => new _IOSinkImpl(target, encoding);
 
   /**
@@ -204,7 +204,7 @@
       }
     }
     if (string.isEmpty) return;
-    add(_encodeString(string, _encoding));
+    add(_encoding.encode(string));
   }
 
   void writeAll(Iterable objects, [String separator = ""]) {
diff --git a/sdk/lib/io/process.dart b/sdk/lib/io/process.dart
index 0f89a30..5ca1597 100644
--- a/sdk/lib/io/process.dart
+++ b/sdk/lib/io/process.dart
@@ -129,7 +129,7 @@
    *
    * The encoding used for decoding `stdout` and `stderr` into text is
    * controlled through [stdoutEncoding] and [stderrEncoding]. The
-   * default encoding is `Encoding.SYSTEM`. If `null` is used no
+   * default encoding is [SYSTEM_ENCODING]. If `null` is used no
    * decoding will happen and the [ProcessResult] will hold binary
    * data.
    *
@@ -144,8 +144,8 @@
        Map<String, String> environment,
        bool includeParentEnvironment: true,
        bool runInShell: false,
-       Encoding stdoutEncoding: Encoding.SYSTEM,
-       Encoding stderrEncoding: Encoding.SYSTEM});
+       Encoding stdoutEncoding: SYSTEM_ENCODING,
+       Encoding stderrEncoding: SYSTEM_ENCODING});
 
 
   /**
@@ -164,8 +164,8 @@
        Map<String, String> environment,
        bool includeParentEnvironment: true,
        bool runInShell: false,
-       Encoding stdoutEncoding: Encoding.SYSTEM,
-       Encoding stderrEncoding: Encoding.SYSTEM});
+       Encoding stdoutEncoding: SYSTEM_ENCODING,
+       Encoding stderrEncoding: SYSTEM_ENCODING});
 
   /**
    * Returns the standard output stream of the process as a [:Stream:].
diff --git a/sdk/lib/io/stdio.dart b/sdk/lib/io/stdio.dart
index d69839e..3725526 100644
--- a/sdk/lib/io/stdio.dart
+++ b/sdk/lib/io/stdio.dart
@@ -30,10 +30,14 @@
 
 
 class _StdinEventSink implements EventSink<String> {
-  Function add;
-  Function addError;
-  Function close;
-  _StdinEventSink(this.add, this.addError, this.close);
+  Function _add;
+  Function _addError;
+  Function _close;
+  _StdinEventSink(this._add, this._addError, this._close);
+
+  void add(String string) => _add(string);
+  void addError(errorEvent) => _addError(errorEvent);
+  void close() => _close();
 }
 
 /**
@@ -54,42 +58,72 @@
    * If end-of-file is reached after some data has already been read, that data
    * is returned.
    */
-  String readLineSync({Encoding encoding: Encoding.SYSTEM,
+  String readLineSync({Encoding encoding: SYSTEM_ENCODING,
                        bool retainNewlines: false}) {
-    var decoder = new StringDecoder(encoding)._decoder;
+    const CR = 13;
+    const LF = 10;
     var line = new StringBuffer();
     bool end = false;
     bool lastCharWasCR = false;
-    var sink = new _StdinEventSink(
-        (char) {
-          if (!retainNewlines && char == '\r') {
-            if (lastCharWasCR) line.write('\r');
-            lastCharWasCR = true;
-            return;
-          } else if (char == '\n') {
-            end = true;
-            if (!retainNewlines) return;
-          } else if (lastCharWasCR) {
-            lastCharWasCR = false;
-            line.write('\r');
-          }
-          line.write(char);
-        },
-        (error) {
-          throw error;
-        }, () {
-          if (lastCharWasCR) line.write('\r');
-        });
+    var error;
+
+    StreamController<List<int>> controller =
+        new StreamController<List<int>>(sync: true);
+    Stream stream = controller.stream.transform(encoding.decoder);
+    stream.listen((String str) {
+      line.write(str);
+    }, onError: (e) {
+      error = e;
+    }, onDone: () {
+      end = true;
+    });
 
     bool empty = true;
     while (!end) {
       int b = readByteSync();
-      if (b >= 0) {
-        empty = false;
-        decoder.handleData([b], sink);
+
+      if (b < 0) {
+        // We didn't write the carriage return in case a line feed would be
+        // the next character. Add it now.
+        if (lastCharWasCR && !retainNewlines) controller.add([CR]);
+        controller.close();
       } else {
-        decoder.handleDone(sink);
-        break;
+        empty = false;
+        // We consider \r\n and \n as new lines.
+        // A \r on its own is treated like a normal character.
+
+        if (b == CR) {
+          if (lastCharWasCR && !retainNewlines) {
+            // We didn't write the carriage return in case a line feed would be
+            // the next character.
+            // Add it now (since we treat it like a normal character now).
+            controller.add([CR]);
+          }
+          // We add the carriage return only if we keep new lines.
+          // Otherwise we need to wait for the next character (in case it is
+          // a line feed).
+          if (retainNewlines) controller.add([b]);
+          lastCharWasCR = true;
+        } else if (b == LF) {
+          end = true;
+          // We don't care if there was a carriage return before. If we keep
+          // the line separators it has already been added to the controller.
+          // Otherwise we don't want it anyway.
+          if (retainNewlines) controller.add([b]);
+          controller.close();
+        } else {
+          // Since the current character is not a line feed we flush the
+          // carriage return we didn't write last iteration.
+          if (lastCharWasCR) {
+            controller.add([CR]);
+            lastCharWasCR = false;
+          }
+          controller.add([b]);
+        }
+      }
+      if (error != null) {
+        // Error during decoding.
+        throw error;
       }
     }
 
diff --git a/sdk/lib/io/string_transformer.dart b/sdk/lib/io/string_transformer.dart
index 5324d69..9178757 100644
--- a/sdk/lib/io/string_transformer.dart
+++ b/sdk/lib/io/string_transformer.dart
@@ -4,357 +4,126 @@
 
 part of dart.io;
 
-/**
- * String encodings.
- */
-class Encoding {
-  static const Encoding UTF_8 = const Encoding._internal("utf-8");
-  static const Encoding ISO_8859_1 = const Encoding._internal("iso-8859-1");
-  static const Encoding ASCII = const Encoding._internal("us-ascii");
-
-  /**
-   * SYSTEM encoding is the current code page on Windows and UTF-8 on
-   * Linux and Mac.
-   */
-  static const Encoding SYSTEM = const Encoding._internal("system");
-
-  // All aliasses (in lowercase) of supported encoding from
-  // http://www.iana.org/assignments/character-sets/character-sets.xml.
-  static Map<String, Encoding> _nameToEncoding = <String, Encoding> {
-    // ISO_8859-1:1987.
-    "iso_8859-1:1987": ISO_8859_1,
-    "iso-ir-100": ISO_8859_1,
-    "iso_8859-1": ISO_8859_1,
-    "iso-8859-1": ISO_8859_1,
-    "latin1": ISO_8859_1,
-    "l1": ISO_8859_1,
-    "ibm819": ISO_8859_1,
-    "cp819": ISO_8859_1,
-    "csisolatin1": ISO_8859_1,
-
-    // US-ASCII.
-    "iso-ir-6": ASCII,
-    "ansi_x3.4-1968": ASCII,
-    "ansi_x3.4-1986": ASCII,
-    "iso_646.irv:1991": ASCII,
-    "iso646-us": ASCII,
-    "us-ascii": ASCII,
-    "us": ASCII,
-    "ibm367": ASCII,
-    "cp367": ASCII,
-    "csascii": ASCII,
-    "ascii": ASCII,  // This is not in the IANA official names.
-
-    // UTF-8.
-    "csutf8": UTF_8,
-    "utf-8": UTF_8
-  };
-
-  /**
-   * Gets an [Encoding] object from the name of the character set
-   * name. The names used are the IANA official names for the
-   * character set (see
-   * http://www.iana.org/assignments/character-sets/character-sets.xml).
-   *
-   * The [name] passed is case insensitive.
-   *
-   * If character set is not supported [:null:] is returned.
-   */
-  static Encoding fromName(String name) {
-    if (name == null) return null;
-    name = name.toLowerCase();
-    return _nameToEncoding[name];
-  }
-
-  /**
-   * Name of the encoding. This will be the lower-case version of one of the
-   * IANA official names for the character set (see
-   * http://www.iana.org/assignments/character-sets/character-sets.xml)
-   */
-  final String name;
-
-  const Encoding._internal(String this.name);
-}
-
-const UTF_8 = Encoding.UTF_8;
-const ISO_8859_1 = Encoding.ISO_8859_1;
-const ASCII = Encoding.ASCII;
+const SYSTEM_ENCODING = const SystemEncoding();
 
 /**
- * Stream transformer that can decode a stream of bytes into a stream of
- * strings using [encoding].
- *
- * Invalid or forbidden byte-sequences will not produce errors, but will instead
- * insert [replacementChar] in the decoded strings.
+ * The system encoding is the current code page on Windows and UTF-8 on
+ * Linux and Mac.
  */
-class StringDecoder implements StreamTransformer<List<int>, String> {
-  var _decoder;
+class SystemEncoding extends Encoding {
+  const SystemEncoding();
 
-  /**
-   * Decodes a stream of bytes into a `String` with an optional
-   * [encoding] and [replacementChar].
-   *
-   * The default value for [encoding] is [Encoding.UTF_8].
-   *
-   * The default value for [replacementChar] is code point U+FFFD.
-   *
-   * Completes with the decoded `String` when the stream is done.
-   */
-  static Future<String> decode(
-      Stream<List<int>> stream,
-      [Encoding encoding = Encoding.UTF_8,
-       int replacementChar = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) {
-    return stream
-        .transform(new StringDecoder(encoding, replacementChar))
-        .fold(
-            new StringBuffer(),
-            (prev, data) => prev..write(data))
-        .then((sb) => sb.toString());
-  }
+  List<int> encode(String input) => encoder.convert(input);
+  String decode(List<int> encoded) => decoder.convert(encoded);
 
-  /**
-   * Create a new [StringDecoder] with an optional [encoding] and
-   * [replacementChar].
-   *
-   * The default value for [encoding] is [Encoding.UTF_8].
-   *
-   * The default value for [replacementChar] is code point U+FFFD.
-   */
-  StringDecoder([Encoding encoding = Encoding.UTF_8, int replacementChar]) {
-    switch (encoding) {
-      case Encoding.UTF_8:
-        if (replacementChar == null) {
-          replacementChar = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT;
-        }
-        _decoder = new Utf8DecoderTransformer(replacementChar);
-        break;
-      case Encoding.ASCII:
-        if (replacementChar == null) {
-          replacementChar = '?'.codeUnitAt(0);
-        } else if (replacementChar > 127) {
-          throw new ArgumentError("Invalid replacement character for ASCII");
-        }
-        _decoder = new _AsciiDecoder(replacementChar);
-        break;
-      case Encoding.ISO_8859_1:
-        if (replacementChar == null) {
-          replacementChar = '?'.codeUnitAt(0);
-        } else if (replacementChar > 255) {
-          throw new ArgumentError(
-              "Invalid replacement character for ISO_8859_1");
-        }
-        _decoder = new _Latin1Decoder(replacementChar);
-        break;
-      case Encoding.SYSTEM:
-        if (Platform.operatingSystem == "windows") {
-          _decoder = new _WindowsCodePageDecoder();
-        } else {
-          if (replacementChar != null) {
-            // TODO(ajohnsen): Handle replacement character.
-            throw new UnsupportedError(
-                "Replacement character is not supported for SYSTEM encoding");
-          }
-          _decoder = new Utf8DecoderTransformer();
-        }
-        break;
-      default:
-        throw new ArgumentError("Unsupported encoding '$encoding'");
-    }
-  }
-
-  Stream<String> bind(Stream<List<int>> stream) => _decoder.bind(stream);
-}
-
-
-/**
- * Stream transformer that can encode a stream of strings info a stream of
- * bytes using [encoding].
- *
- * Strings that cannot be represented in the given encoding will result in an
- * error and a close event on the stream.
- */
-class StringEncoder implements StreamTransformer<String, List<int>> {
-  var _encoder;
-
-  /**
-   * Create a new [StringDecoder] with an optional [encoding] and
-   * [replacementChar].
-   */
-  StringEncoder([Encoding encoding = Encoding.UTF_8]) {
-    switch (encoding) {
-      case Encoding.UTF_8:
-        _encoder = new Utf8EncoderTransformer();
-        break;
-      case Encoding.ASCII:
-        _encoder = new _AsciiEncoder();
-        break;
-      case Encoding.ISO_8859_1:
-        _encoder = new _Latin1Encoder();
-        break;
-      case Encoding.SYSTEM:
-        if (Platform.operatingSystem == "windows") {
-          _encoder = new _WindowsCodePageEncoder();
-        } else {
-          _encoder = new Utf8EncoderTransformer();
-        }
-        break;
-      default:
-        throw new ArgumentError("Unsupported encoding '$encoding'");
-    }
-  }
-
-  Stream<List<int>> bind(Stream<String> stream) => _encoder.bind(stream);
-}
-
-
-// Utility function to synchronously decode a list of bytes.
-String _decodeString(List<int> bytes, [Encoding encoding = Encoding.UTF_8]) {
-  if (bytes.length == 0) return "";
-  var string;
-  var error;
-  var controller = new StreamController(sync: true);
-  controller.stream
-    .transform(new StringDecoder(encoding))
-    .listen((data) => string = data,
-            onError: (e) => error = e);
-  controller.add(bytes);
-  controller.close();
-  if (error != null) throw error;
-  assert(string != null);
-  return string;
-}
-
-
-// Utility function to synchronously decode a utf8-encoded list of bytes,
-// throwing on error.
-String _decodeUtf8Strict(List<int> bytes) {
-  if (bytes.length == 0) return "";
-  var string;
-  var error;
-  var controller = new StreamController(sync: true);
-  controller.stream
-    .transform(new Utf8DecoderTransformer(null))
-    .listen((data) => string = data,
-            onError: (e) => error = e);
-  controller.add(bytes);
-  controller.close();
-  if (error != null) throw error;
-  assert(string != null);
-  return string;
-}
-
-
-// Utility function to synchronously encode a String.
-// Will throw an exception if the encoding is invalid.
-List<int> _encodeString(String string, [Encoding encoding = Encoding.UTF_8]) {
-  if (string.length == 0) return [];
-  var bytes;
-  var controller = new StreamController(sync: true);
-  controller.stream
-    .transform(new StringEncoder(encoding))
-    .listen((data) => bytes = data);
-  controller.add(string);
-  controller.close();
-  assert(bytes != null);
-  return bytes;
-}
-
-
-abstract class _SingleByteDecoder
-    extends StreamEventTransformer<List<int>, String> {
-  final int _replacementChar;
-
-  _SingleByteDecoder(this._replacementChar);
-
-  void handleData(List<int> data, EventSink<String> sink) {
-    var buffer = new List<int>(data.length);
-    for (int i = 0; i < data.length; i++) {
-      int char = _decodeByte(data[i]);
-      if (char < 0) char = _replacementChar;
-      buffer[i] = char;
-    }
-    sink.add(new String.fromCharCodes(buffer));
-  }
-
-  int _decodeByte(int byte);
-}
-
-
-// Utility class for decoding ascii data delivered as a stream of
-// bytes.
-class _AsciiDecoder extends _SingleByteDecoder {
-  _AsciiDecoder(int replacementChar) : super(replacementChar);
-
-  int _decodeByte(int byte) => ((byte & 0x7f) == byte) ? byte : -1;
-}
-
-
-// Utility class for decoding Latin-1 data delivered as a stream of
-// bytes.
-class _Latin1Decoder extends _SingleByteDecoder {
-  _Latin1Decoder(int replacementChar) : super(replacementChar);
-
-  int _decodeByte(int byte) => ((byte & 0xFF) == byte) ? byte : -1;
-}
-
-
-abstract class _SingleByteEncoder
-    extends StreamEventTransformer<String, List<int>> {
-  void handleData(String data, EventSink<List<int>> sink) {
-    var bytes = _encode(data);
-    if (bytes == null) {
-      sink.addError(new FormatException("Invalid character for encoding"));
-      sink.close();
+  Converter<String, List<int>> get encoder {
+    if (Platform.operatingSystem == "windows") {
+      return const _WindowsCodePageEncoder();
     } else {
-      sink.add(bytes);
+      return const Utf8Encoder();
     }
   }
 
-  List<int> _encode(String string);
-}
-
-
-// Utility class for encoding a string into an ASCII byte stream.
-class _AsciiEncoder extends _SingleByteEncoder {
-  List<int> _encode(String string) {
-    var bytes = string.codeUnits;
-    for (var byte in bytes) {
-      if (byte > 127) return null;
+  Converter<List<int>, String> get decoder {
+    if (Platform.operatingSystem == "windows") {
+      return const _WindowsCodePageDecoder();
+    } else {
+      return const Utf8Decoder();
     }
-    return bytes;
   }
 }
 
+class _WindowsCodePageEncoder extends Converter<String, List<int>> {
 
-// Utility class for encoding a string into a Latin1 byte stream.
-class _Latin1Encoder extends _SingleByteEncoder {
-  List<int> _encode(String string) {
-    var bytes = string.codeUnits;
-    for (var byte in bytes) {
-      if (byte > 255) return null;
+  const _WindowsCodePageEncoder();
+
+  List<int> convert(String input) {
+    List<int> encoded = _encodeString(input);
+    if (encoded == null) {
+      throw new FormatException("Invalid character for encoding");
     }
-    return bytes;
+    return encoded;
   }
-}
 
+  /**
+   * Starts a chunked conversion.
+   */
+  StringConversionSink startChunkedConversion(
+      ChunkedConversionSink<List<int>> sink) {
+    return new _WindowsCodePageEncoderSink(sink);
+  }
 
-// Utility class for encoding a string into a current windows
-// code page byte list.
-// Implemented on top of a _SingleByteEncoder, even though it's not really a
-// single byte encoder, to avoid copying boilerplate.
-class _WindowsCodePageEncoder extends _SingleByteEncoder {
-  List<int> _encode(String string) => _encodeString(string);
+  // Override the base-class' bind, to provide a better type.
+  Stream<List<int>> bind(Stream<String> stream) => super.bind(stream);
 
   external static List<int> _encodeString(String string);
 }
 
+class _WindowsCodePageEncoderSink extends StringConversionSinkBase {
+  // TODO(floitsch): provide more efficient conversions when the input is
+  // not a String.
 
-// Utility class for decoding Windows current code page data delivered
-// as a stream of bytes.
-class _WindowsCodePageDecoder extends StreamEventTransformer<List<int>, String> {
-  void handleData(List<int> data, EventSink<String> sink) {
-    sink.add(_decodeBytes(data));
+  final ChunkedConversionSink<List<int>> _sink;
+
+  _WindowsCodePageEncoderSink(this._sink);
+
+  void close() {
+    _sink.close();
   }
 
+  void add(String string) {
+    List<int> encoded = _WindowsCodePageEncoder._encodeString(string);
+    if (encoded == null) {
+      throw new FormatException("Invalid character for encoding");
+    }
+    _sink.add(encoded);
+  }
+
+  void addSlice(String source, int start, int end, bool isLast) {
+    if (start != 0 || end != source.length) {
+      source = source.substring(start, end);
+    }
+    add(source);
+    if (isLast) close();
+  }
+}
+
+
+class _WindowsCodePageDecoder extends Converter<List<int>, String> {
+
+  const _WindowsCodePageDecoder();
+
+  String convert(List<int> input) {
+    return _decodeBytes(input);
+  }
+
+  /**
+   * Starts a chunked conversion.
+   */
+  ByteConversionSink startChunkedConversion(
+      ChunkedConversionSink<String> sink) {
+    return new _WindowsCodePageDecoderSink(sink);
+  }
+
+  // Override the base-class' bind, to provide a better type.
+  Stream<String> bind(Stream<List<int>> stream) => super.bind(stream);
+
   external static String _decodeBytes(List<int> bytes);
 }
+
+class _WindowsCodePageDecoderSink extends ByteConversionSinkBase {
+  // TODO(floitsch): provide more efficient conversions when the input is
+  // a slice.
+
+  final ChunkedConversionSink<String> _sink;
+
+  _WindowsCodePageDecoderSink(this._sink);
+
+  void close() {
+    _sink.close();
+  }
+
+  void add(List<int> bytes) {
+    _sink.add(_WindowsCodePageDecoder._decodeBytes(bytes));
+  }
+}
diff --git a/sdk/lib/io/websocket_impl.dart b/sdk/lib/io/websocket_impl.dart
index aec2919..f85ddf2 100644
--- a/sdk/lib/io/websocket_impl.dart
+++ b/sdk/lib/io/websocket_impl.dart
@@ -95,7 +95,7 @@
               _currentMessageType = _WebSocketMessageType.TEXT;
               _controller = new StreamController(sync: true);
               _controller.stream
-                  .transform(new Utf8DecoderTransformer(null))
+                  .transform(UTF8.decoder)
                   .fold(new StringBuffer(), (buffer, str) => buffer..write(str))
                   .then((buffer) {
                     sink.add(buffer.toString());
@@ -304,7 +304,7 @@
             throw new WebSocketException("Protocol error");
           }
           if (_controlPayload.length > 2) {
-            closeReason = _decodeUtf8Strict(_controlPayload.sublist(2));
+            closeReason = UTF8.decode(_controlPayload.sublist(2));
           }
         }
         _state = CLOSED;
@@ -463,7 +463,7 @@
     if (message != null) {
       if (message is String) {
         opcode = _WebSocketOpcode.TEXT;
-        data = _encodeString(message);
+        data = UTF8.encode(message);
       } else {
         if (message is !List<int>) {
           throw new ArgumentError(message);
@@ -486,7 +486,7 @@
       data.add((code >> 8) & 0xFF);
       data.add(code & 0xFF);
       if (reason != null) {
-        data.addAll(_encodeString(reason));
+        data.addAll(UTF8.encode(reason));
       }
     }
     addFrame(_WebSocketOpcode.CLOSE, data, sink);
diff --git a/tests/language/language.status b/tests/language/language.status
index 70f61d0..1d8e778 100644
--- a/tests/language/language.status
+++ b/tests/language/language.status
@@ -258,3 +258,6 @@
 
 [ $compiler == dart2js ]
 null_test/none: Fail  # Issue 12482
+
+[ $compiler == none && $runtime == drt ]
+vm/reflect_core_vm_test: Fail  # Temporarily marked as fail.
diff --git a/tests/language/optimized_isempty_test.dart b/tests/language/optimized_isempty_test.dart
new file mode 100644
index 0000000..d223c8b
--- /dev/null
+++ b/tests/language/optimized_isempty_test.dart
@@ -0,0 +1,21 @@
+// Copyright (c) 2013, 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.
+// VMOptions=--optimization-counter-threshold=10 --no-use-osr
+
+// Test optimization and polymorphic inlining of String.isEmpty.
+
+import "package:expect/expect.dart";
+
+test(s) => s.isEmpty;
+
+main() {
+  var x = "abc";
+  var y = [123, 12345, 765];
+  Expect.equals(false, test(x));
+  Expect.equals(false, test(y));
+  for (var i=0; i<20; i++) test(x);
+  Expect.equals(false, test(x));
+  Expect.equals(false, test(y));
+}
+
diff --git a/tests/language/reflect_core_vm_test.dart b/tests/language/reflect_core_vm_test.dart
new file mode 100644
index 0000000..d6e52f1
--- /dev/null
+++ b/tests/language/reflect_core_vm_test.dart
@@ -0,0 +1,20 @@
+// Copyright (c) 2013, 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.
+
+// Test reflection of private functions in core classes.
+
+import "package:expect/expect.dart";
+import "dart:mirrors";
+
+main() {
+  var s = "string";
+  var im = reflect(s);
+  try {
+    im.invoke(const Symbol("_setAt"), [0, 65]);
+    Expect.isTrue(false);  // Unreachable.
+  } catch (e) {
+    Expect.equals(true, e is NoSuchMethodError);
+  }
+}
+
diff --git a/tests/lib/convert/encoding_test.dart b/tests/lib/convert/encoding_test.dart
new file mode 100644
index 0000000..cbdf72d
--- /dev/null
+++ b/tests/lib/convert/encoding_test.dart
@@ -0,0 +1,39 @@
+// Copyright (c) 2013, 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 "package:expect/expect.dart";
+import 'dart:async';
+import 'dart:convert';
+import 'unicode_tests.dart';
+import '../../async_helper.dart';
+
+void runTest(List<int> bytes, expected) {
+  var controller = new StreamController();
+  asyncStart();
+  UTF8.decodeStream(controller.stream).then((decoded) {
+    Expect.equals(expected, decoded);
+    asyncEnd();
+  });
+  int i = 0;
+  while (i < bytes.length) {
+    List nextChunk = [];
+    for (int j = 0; j < 3; j++) {
+      if (i < bytes.length) {
+        nextChunk.add(bytes[i]);
+        i++;
+      }
+    }
+    controller.add(nextChunk);
+  }
+  controller.close();
+}
+
+
+main() {
+  for (var test in UNICODE_TESTS) {
+    var bytes = test[0];
+    var expected = test[1];
+    runTest(bytes, expected);
+  }
+}
diff --git a/tests/standalone/coverage_test.dart b/tests/standalone/coverage_test.dart
index ecf92ea..c9a5c5f 100644
--- a/tests/standalone/coverage_test.dart
+++ b/tests/standalone/coverage_test.dart
@@ -65,11 +65,11 @@
     coverageToolProcess = process;
     coverageToolProcess.stdin.close();
     var stdoutStringStream = coverageToolProcess.stdout
-        .transform(new StringDecoder())
+        .transform(UTF8.decoder)
         .transform(new LineSplitter());
 
     var stderrStringStream = coverageToolProcess.stderr
-        .transform(new StringDecoder())
+        .transform(UTF8.decoder)
         .transform(new LineSplitter());
 
     // Wait for 3 future events: stdout and stderr streams of the coverage
diff --git a/tests/standalone/debugger/debug_lib.dart b/tests/standalone/debugger/debug_lib.dart
index 7be6854..0377ae9 100644
--- a/tests/standalone/debugger/debug_lib.dart
+++ b/tests/standalone/debugger/debug_lib.dart
@@ -393,7 +393,7 @@
 
   Debugger(this.targetProcess, this.script) {
     var stdoutStringStream = targetProcess.stdout
-        .transform(new StringDecoder())
+        .transform(UTF8.decoder)
         .transform(new LineSplitter());
     stdoutStringStream.listen((line) {
       print("TARG: $line");
@@ -406,7 +406,7 @@
     });
 
     var stderrStringStream = targetProcess.stderr
-        .transform(new StringDecoder())
+        .transform(UTF8.decoder)
         .transform(new LineSplitter());
     stderrStringStream.listen((line) {
       print("TARG: $line");
@@ -542,7 +542,7 @@
     Socket.connect("127.0.0.1", portNumber).then((s) {
         s.setOption(SocketOption.TCP_NODELAY, true);
         this.socket = s;
-        var stringStream = socket.transform(new StringDecoder());
+        var stringStream = socket.transform(UTF8.decoder);
         stringStream.listen((str) {
             try {
               responses.append(str);
diff --git a/tests/standalone/io/file_error_test.dart b/tests/standalone/io/file_error_test.dart
index 27753d6..6ebb5b9 100644
--- a/tests/standalone/io/file_error_test.dart
+++ b/tests/standalone/io/file_error_test.dart
@@ -5,6 +5,7 @@
 // Dart test program for testing error handling in file I/O.
 
 import "package:expect/expect.dart";
+import "dart:convert";
 import "dart:io";
 import "dart:isolate";
 
@@ -205,7 +206,7 @@
   Expect.throws(() => file.readAsStringSync(),
                 (e) => checkOpenNonExistentFileException(e));
 
-  var readAsStringFuture = file.readAsString(encoding: Encoding.ASCII);
+  var readAsStringFuture = file.readAsString(encoding: ASCII);
   readAsStringFuture.then((data) => Expect.fail("Unreachable code"))
   .catchError((error) {
     checkOpenNonExistentFileException(error);
@@ -226,7 +227,7 @@
   Expect.throws(() => file.readAsLinesSync(),
                 (e) => checkOpenNonExistentFileException(e));
 
-  var readAsLinesFuture = file.readAsLines(encoding: Encoding.ASCII);
+  var readAsLinesFuture = file.readAsLines(encoding: ASCII);
   readAsLinesFuture.then((data) => Expect.fail("Unreachable code"))
   .catchError((error) {
     checkOpenNonExistentFileException(error);
diff --git a/tests/standalone/io/file_input_stream_test.dart b/tests/standalone/io/file_input_stream_test.dart
index 021e19e..824cfce 100644
--- a/tests/standalone/io/file_input_stream_test.dart
+++ b/tests/standalone/io/file_input_stream_test.dart
@@ -20,7 +20,7 @@
   File file = new File(fileName);
   int linesRead = 0;
   var lineStream = file.openRead()
-    .transform(new StringDecoder())
+    .transform(UTF8.decoder)
     .transform(new LineSplitter());
   lineStream.listen((line) {
     linesRead++;
@@ -232,7 +232,7 @@
   File file = new File(fileName);
   Expect.equals(length, file.openSync().lengthSync());
   var lineStream = file.openRead()
-    .transform(new StringDecoder())
+    .transform(UTF8.decoder)
     .transform(new LineSplitter());
   int lineCount = 0;
   lineStream.listen(
diff --git a/tests/standalone/io/file_test.dart b/tests/standalone/io/file_test.dart
index 6a16efc..28001ed 100644
--- a/tests/standalone/io/file_test.dart
+++ b/tests/standalone/io/file_test.dart
@@ -7,6 +7,7 @@
 import "package:expect/expect.dart";
 import "package:path/path.dart";
 import 'dart:async';
+import 'dart:convert';
 import 'dart:collection';
 import 'dart:io';
 import 'dart:isolate';
@@ -393,13 +394,13 @@
     List<int> buffer = content.codeUnits;
     var output = file.openWrite();
     output.write("abcdABCD");
-    output.encoding = UTF_8;
+    output.encoding = UTF8;
     output.write("abcdABCD");
-    output.encoding = ISO_8859_1;
+    output.encoding = LATIN1;
     output.write("abcdABCD");
     output.encoding = ASCII;
     output.write("abcdABCD");
-    output.encoding = UTF_8;
+    output.encoding = UTF8;
     output.write("æøå");
     output.close();
     output.done.then((_) {
@@ -985,16 +986,16 @@
     });
     var name = getFilename("tests/vm/data/fixed_length_file");
     var f = new File(name);
-    f.readAsString(encoding: UTF_8).then((text) {
+    f.readAsString(encoding: UTF8).then((text) {
       Expect.isTrue(text.endsWith("42 bytes."));
       Expect.equals(42, text.length);
       var name = getDataFilename("tests/standalone/io/read_as_text.dat");
       var f = new File(name);
-      f.readAsString(encoding: UTF_8).then((text) {
+      f.readAsString(encoding: UTF8).then((text) {
         Expect.equals(6, text.length);
         var expected = [955, 120, 46, 32, 120, 10];
         Expect.listEquals(expected, text.codeUnits);
-        f.readAsString(encoding: ISO_8859_1).then((text) {
+        f.readAsString(encoding: LATIN1).then((text) {
           Expect.equals(7, text.length);
           var expected = [206, 187, 120, 46, 32, 120, 10];
           Expect.listEquals(expected, text.codeUnits);
@@ -1017,7 +1018,7 @@
     });
     var name = getFilename("tests/vm/data/empty_file");
     var f = new File(name);
-    f.readAsString(encoding: UTF_8).then((text) {
+    f.readAsString(encoding: UTF8).then((text) {
       port.toSendPort().send(text.length);
       return true;
     });
@@ -1033,11 +1034,18 @@
     Expect.equals(6, text.length);
     var expected = [955, 120, 46, 32, 120, 10];
     Expect.listEquals(expected, text.codeUnits);
-    text = new File(name).readAsStringSync(encoding: ASCII);
-    // Default replacement character is '?', char code 63.
-    expected = [63, 63, 120, 46, 32, 120, 10];
+    // First character is not ASCII. The default ASCII decoder will throw.
+    Expect.throws(() => new File(name).readAsStringSync(encoding: ASCII),
+                  (e) => e is FormatException);
+    // We can use an ASCII decoder that inserts the replacement character.
+    var lenientAscii = const AsciiCodec(allowInvalid: true);
+    text = new File(name).readAsStringSync(encoding: lenientAscii);
+    // Default replacement character is the Unicode replacement character.
+    expected = [UNICODE_REPLACEMENT_CHARACTER_RUNE,
+                UNICODE_REPLACEMENT_CHARACTER_RUNE,
+                120, 46, 32, 120, 10];
     Expect.listEquals(expected, text.codeUnits);
-    text = new File(name).readAsStringSync(encoding: ISO_8859_1);
+    text = new File(name).readAsStringSync(encoding: LATIN1);
     expected = [206, 187, 120, 46, 32, 120, 10];
     Expect.equals(7, text.length);
     Expect.listEquals(expected, text.codeUnits);
@@ -1057,7 +1065,7 @@
     });
     var name = getFilename("tests/vm/data/fixed_length_file");
     var f = new File(name);
-    f.readAsLines(encoding: UTF_8).then((lines) {
+    f.readAsLines(encoding: UTF8).then((lines) {
       Expect.equals(1, lines.length);
       var line = lines[0];
       Expect.isTrue(line.endsWith("42 bytes."));
@@ -1091,10 +1099,10 @@
     var readAsBytesFuture = f.readAsBytes();
     readAsBytesFuture.then((bytes) => Expect.fail("no bytes expected"))
     .catchError((e) {
-      var readAsStringFuture = f.readAsString(encoding: UTF_8);
+      var readAsStringFuture = f.readAsString(encoding: UTF8);
       readAsStringFuture.then((text) => Expect.fail("no text expected"))
       .catchError((e) {
-        var readAsLinesFuture = f.readAsLines(encoding: UTF_8);
+        var readAsLinesFuture = f.readAsLines(encoding: UTF8);
         readAsLinesFuture.then((lines) => Expect.fail("no lines expected"))
         .catchError((e) {
           port.toSendPort().send(1);
diff --git a/tests/standalone/io/http_auth_digest_test.dart b/tests/standalone/io/http_auth_digest_test.dart
index 2a3828d..5512cd0 100644
--- a/tests/standalone/io/http_auth_digest_test.dart
+++ b/tests/standalone/io/http_auth_digest_test.dart
@@ -7,7 +7,6 @@
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
-import 'dart:utf';
 
 class Server {
   HttpServer server;
diff --git a/tests/standalone/io/http_auth_test.dart b/tests/standalone/io/http_auth_test.dart
index 9869a94..d259bdf 100644
--- a/tests/standalone/io/http_auth_test.dart
+++ b/tests/standalone/io/http_auth_test.dart
@@ -7,7 +7,7 @@
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
-import 'dart:utf';
+import 'dart:convert';
 
 class Server {
   HttpServer server;
@@ -42,7 +42,7 @@
           List<String> tokens = authorization.split(" ");
           Expect.equals("Basic", tokens[0]);
           String auth =
-              CryptoUtils.bytesToBase64(encodeUtf8("$username:$password"));
+              CryptoUtils.bytesToBase64(UTF8.encode("$username:$password"));
           if (passwordChanged && auth != tokens[1]) {
             response.statusCode = HttpStatus.UNAUTHORIZED;
             response.headers.set(HttpHeaders.WWW_AUTHENTICATE,
diff --git a/tests/standalone/io/http_proxy_test.dart b/tests/standalone/io/http_proxy_test.dart
index 3b56004..81806ab 100644
--- a/tests/standalone/io/http_proxy_test.dart
+++ b/tests/standalone/io/http_proxy_test.dart
@@ -7,7 +7,7 @@
 import "package:path/path.dart";
 import "dart:async";
 import "dart:io";
-import 'dart:utf';
+import 'dart:convert';
 
 class Server {
   HttpServer server;
@@ -163,7 +163,7 @@
               List<String> tokens = authorization.split(" ");
               Expect.equals("Basic", tokens[0]);
               String auth =
-                  CryptoUtils.bytesToBase64(encodeUtf8("$username:$password"));
+                  CryptoUtils.bytesToBase64(UTF8.encode("$username:$password"));
               if (auth != tokens[1]) {
                 basicAuthenticationRequired(request);
                 return;
diff --git a/tests/standalone/io/process_run_output_test.dart b/tests/standalone/io/process_run_output_test.dart
index efa9892..28d9fa9 100644
--- a/tests/standalone/io/process_run_output_test.dart
+++ b/tests/standalone/io/process_run_output_test.dart
@@ -6,10 +6,11 @@
 // non-interactive processes started with Process.run.
 
 import "package:expect/expect.dart";
+import "dart:convert";
 import "dart:io";
 import "process_test_util.dart";
 
-checkOutput(encoding, output) {
+checkOutput(String encoding, output) {
   if (encoding == 'ascii') {
     Expect.equals(output, 'abc');
   } else if (encoding == 'latin1') {
@@ -22,14 +23,14 @@
   }
 }
 
-test(scriptFile, encoding, stream) {
+test(scriptFile, String encoding, stream) {
   var enc;
   if (encoding == 'ascii') {
-    enc = Encoding.ASCII;
+    enc = ASCII;
   } else if (encoding == 'latin1') {
-    enc = Encoding.ISO_8859_1;
+    enc = LATIN1;
   } else if (encoding == 'utf8') {
-    enc = Encoding.UTF_8;
+    enc = UTF8;
   } else if (encoding == 'binary') {
     enc = null;
   }
diff --git a/tests/standalone/io/process_std_io_script2.dart b/tests/standalone/io/process_std_io_script2.dart
index db57929..0bd1a3e 100644
--- a/tests/standalone/io/process_std_io_script2.dart
+++ b/tests/standalone/io/process_std_io_script2.dart
@@ -5,6 +5,7 @@
 // Utility script to echo strings in various formats to stdout or
 // stderr.
 
+import "dart:convert";
 import "dart:io";
 
 writeData(data, encoding, stream) {
@@ -34,11 +35,11 @@
   if (options.arguments.length > 1) {
     var stream = options.arguments[1];
     if (options.arguments[0] == "ascii") {
-      writeData(asciiString, Encoding.ASCII, stream);
+      writeData(asciiString, ASCII, stream);
     } else if (options.arguments[0] == "latin1") {
-      writeData(latin1String, Encoding.ISO_8859_1, stream);
+      writeData(latin1String, LATIN1, stream);
     } else if (options.arguments[0] == "utf8") {
-      writeData(utf8String, Encoding.UTF_8, stream);
+      writeData(utf8String, UTF8, stream);
     } else if (options.arguments[0] == "binary") {
       writeData(binary, null, stream);
     }
diff --git a/tests/standalone/io/process_stdin_transform_unsubscribe_script.dart b/tests/standalone/io/process_stdin_transform_unsubscribe_script.dart
index 06b42d8..910af04 100644
--- a/tests/standalone/io/process_stdin_transform_unsubscribe_script.dart
+++ b/tests/standalone/io/process_stdin_transform_unsubscribe_script.dart
@@ -10,7 +10,7 @@
 main() {
   var subscription;
   subscription = stdin
-      .transform(new StringDecoder())
+      .transform(UTF8.decoder)
       .transform(new LineSplitter())
       .listen((String line) {
           // Unsubscribe after the first line.
diff --git a/tests/standalone/io/regress_10026_test.dart b/tests/standalone/io/regress_10026_test.dart
index 6c386c7..1b7644c 100644
--- a/tests/standalone/io/regress_10026_test.dart
+++ b/tests/standalone/io/regress_10026_test.dart
@@ -4,6 +4,7 @@
 
 import "package:expect/expect.dart";
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 import 'dart:isolate';
 
@@ -13,7 +14,7 @@
     var controller = new StreamController(sync: true);
     controller.stream
         .transform(ZLIB.decoder)
-        .transform(new StringDecoder())
+        .transform(UTF8.decoder)
         .fold(new StringBuffer(), (buffer, s) {
           buffer.write(s);
           return buffer;
diff --git a/tests/standalone/io/secure_socket_renegotiate_client.dart b/tests/standalone/io/secure_socket_renegotiate_client.dart
index 49d9c99..0c72412 100644
--- a/tests/standalone/io/secure_socket_renegotiate_client.dart
+++ b/tests/standalone/io/secure_socket_renegotiate_client.dart
@@ -44,7 +44,7 @@
       expectEquals('CN=localhost', certificate.subject);
       expectEquals('CN=myauthority', certificate.issuer);
       StreamIterator<String> input = new StreamIterator(socket
-          .transform(new StringDecoder())
+          .transform(UTF8.decoder)
           .transform(new LineSplitter()));
       socket.writeln('first');
       input.moveNext()
diff --git a/tests/standalone/io/secure_socket_renegotiate_test.dart b/tests/standalone/io/secure_socket_renegotiate_test.dart
index 54736a8..ee115a9 100644
--- a/tests/standalone/io/secure_socket_renegotiate_test.dart
+++ b/tests/standalone/io/secure_socket_renegotiate_test.dart
@@ -30,7 +30,7 @@
         Expect.isNull(socket.peerCertificate);
 
         StreamIterator<String> input =
-            new StreamIterator(socket.transform(new StringDecoder())
+            new StreamIterator(socket.transform(UTF8.decoder)
                                      .transform(new LineSplitter()));
         input.moveNext().then((success) {
           Expect.isTrue(success);
diff --git a/tests/standalone/io/stdin_sync_script.dart b/tests/standalone/io/stdin_sync_script.dart
index d2bc4ad..ed60a9c 100644
--- a/tests/standalone/io/stdin_sync_script.dart
+++ b/tests/standalone/io/stdin_sync_script.dart
@@ -2,6 +2,7 @@
 // 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:convert";
 import "dart:io";
 import "dart:json";
 
@@ -9,7 +10,7 @@
   var arguments = new Options().arguments;
   int i = 0;
   String line;
-  while ((line = stdin.readLineSync(encoding: Encoding.UTF_8)) != null) {
+  while ((line = stdin.readLineSync(encoding: UTF8)) != null) {
     if (parse(arguments[i]) != line) throw "bad line at $i: ${line.codeUnits}";
     i++;
   }
diff --git a/tests/standalone/io/stdin_sync_test.dart b/tests/standalone/io/stdin_sync_test.dart
index 0ac4e9d..c0477c0 100644
--- a/tests/standalone/io/stdin_sync_test.dart
+++ b/tests/standalone/io/stdin_sync_test.dart
@@ -17,14 +17,14 @@
       process.stdin.write(line);
       process.stdin.close();
       process.stderr
-          .transform(new StringDecoder())
+          .transform(UTF8.decoder)
           .transform(new LineSplitter())
           .fold(new StringBuffer(), (b, d) => b..write(d))
           .then((data) {
             if (data.toString() != '') throw "Bad output: '$data'";
           });
       process.stdout
-          .transform(new StringDecoder())
+          .transform(UTF8.decoder)
           .transform(new LineSplitter())
           .fold(new StringBuffer(), (b, d) => b..write(d))
           .then((data) {
diff --git a/tests/standalone/io/stdout_stderr_test.dart b/tests/standalone/io/stdout_stderr_test.dart
index 1f7ac91..296a8d6 100644
--- a/tests/standalone/io/stdout_stderr_test.dart
+++ b/tests/standalone/io/stdout_stderr_test.dart
@@ -4,12 +4,13 @@
 
 import "package:expect/expect.dart";
 import "dart:async";
+import "dart:convert";
 import "dart:io";
 
 callIOSink(IOSink sink) {
   // Call all methods on IOSink.
-  sink.encoding = Encoding.ASCII;
-  Expect.equals(Encoding.ASCII, sink.encoding);
+  sink.encoding = ASCII;
+  Expect.equals(ASCII, sink.encoding);
   sink.write("Hello\n");
   sink.writeln("Hello");
   sink.writeAll(["H", "e", "l", "lo\n"]);
diff --git a/tests/standalone/io/string_decoder_test.dart b/tests/standalone/io/string_decoder_test.dart
deleted file mode 100644
index 6e96000..0000000
--- a/tests/standalone/io/string_decoder_test.dart
+++ /dev/null
@@ -1,94 +0,0 @@
-// Copyright (c) 2013, 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 "package:expect/expect.dart";
-import "dart:async";
-import "dart:io";
-
-void testTransform() {
-  // Code point U+10FFFF is the largest code point supported by Dart.
-  var controller = new StreamController(sync: true);
-  controller.add([0xf0, 0x90, 0x80, 0x80]);  // U+10000
-  controller.add([0xf4, 0x8f, 0xbf, 0xbf]);  // U+10FFFF
-  controller.add([0xf4, 0x90, 0x80, 0x80]);  // U+110000
-  controller.add([0xfa, 0x80, 0x80, 0x80, 0x80]);  //  U+2000000
-  controller.add([0xfd, 0x80, 0x80, 0x80, 0x80, 0x80]);  // U+40000000
-  controller.close();
-
-  var decoder = new StringDecoder(Encoding.UTF_8, '?'.codeUnitAt(0));
-  var stream = controller.stream.transform(decoder);
-  stream.fold(
-      new StringBuffer(),
-      (b, e) {
-        b.write(e);
-        return b;
-      })
-      .then((b) => b.toString())
-      .then((decoded) {
-        Expect.equals(8, decoded.length);
-
-        var replacementChar = '?'.codeUnitAt(0);
-        Expect.equals(0xd800, decoded.codeUnitAt(0));
-        Expect.equals(0xdc00, decoded.codeUnitAt(1));
-        Expect.equals(0xdbff, decoded.codeUnitAt(2));
-        Expect.equals(0xdfff, decoded.codeUnitAt(3));
-        Expect.equals(replacementChar, decoded.codeUnitAt(4));
-        Expect.equals(replacementChar, decoded.codeUnitAt(5));
-        Expect.equals(replacementChar, decoded.codeUnitAt(6));
-        Expect.equals(replacementChar, decoded.codeUnitAt(7));
-      });
-}
-
-void testDecode() {
-  // Code point U+10FFFF is the largest code point supported by Dart.
-  var controller = new StreamController(sync: true);
-  controller.add([0xf0, 0x90, 0x80, 0x80]);  // U+10000
-  controller.add([0xf4, 0x8f, 0xbf, 0xbf]);  // U+10FFFF
-  controller.add([0xf4, 0x90, 0x80, 0x80]);  // U+110000
-  controller.add([0xfa, 0x80, 0x80, 0x80, 0x80]);  //  U+2000000
-  controller.add([0xfd, 0x80, 0x80, 0x80, 0x80, 0x80]);  // U+40000000
-  controller.close();
-
-  StringDecoder.decode(controller.stream,
-                       Encoding.UTF_8,
-                       '?'.codeUnitAt(0)).then((decoded) {
-    Expect.equals(8, decoded.length);
-
-    var replacementChar = '?'.codeUnitAt(0);
-    Expect.equals(0xd800, decoded.codeUnitAt(0));
-    Expect.equals(0xdc00, decoded.codeUnitAt(1));
-    Expect.equals(0xdbff, decoded.codeUnitAt(2));
-    Expect.equals(0xdfff, decoded.codeUnitAt(3));
-    Expect.equals(replacementChar, decoded.codeUnitAt(4));
-    Expect.equals(replacementChar, decoded.codeUnitAt(5));
-    Expect.equals(replacementChar, decoded.codeUnitAt(6));
-    Expect.equals(replacementChar, decoded.codeUnitAt(7));
-  });
-}
-
-void testInvalid() {
-  void invalid(var bytes, var outputLength) {
-    var controller = new StreamController(sync: true);
-    controller.add(bytes);
-    controller.close();
-    controller.stream.transform(new StringDecoder()).listen((string) {
-      Expect.equals(outputLength, string.length);
-      for (var i = 0; i < outputLength; i++) {
-        Expect.equals(0xFFFD, string.codeUnitAt(i));
-      }
-    });
-  }
-
-  invalid([0x80], 1);
-  invalid([0xff], 1);
-  invalid([0xf0, 0xc0], 1);
-  invalid([0xc0, 0x80], 1);
-  invalid([0xfd, 0x80, 0x80], 3); // Unfinished encoding.
-}
-
-void main() {
-  testTransform();
-  testDecode();
-  testInvalid();
-}
diff --git a/tests/standalone/io/string_transformer_test.dart b/tests/standalone/io/string_transformer_test.dart
deleted file mode 100644
index eb6d168..0000000
--- a/tests/standalone/io/string_transformer_test.dart
+++ /dev/null
@@ -1,200 +0,0 @@
-// Copyright (c) 2012, 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";
-import "dart:convert";
-import "dart:io";
-import "dart:isolate";
-import "dart:utf";
-
-import "package:expect/expect.dart";
-
-void main() {
-  testUtf8();
-  testLatin1();
-  testAscii();
-  testReadLine1();
-  testReadLine2();
-  testErrorHandler();
-  testLatin1EncoderError();
-}
-
-void testUtf8() {
-  List<int> data = [0x01,
-                    0x7f,
-                    0xc2, 0x80,
-                    0xdf, 0xbf,
-                    0xe0, 0xa0, 0x80,
-                    0xef, 0xbf, 0xbf,
-                    0xf0, 0x9d, 0x84, 0x9e,
-                    0x100, -0x1, -0xFF];
-  var controller = new StreamController(sync: true);
-  controller.add(data);
-  controller.close();
-  var stringStream = controller.stream
-    .transform(new StringDecoder(Encoding.UTF_8));
-  stringStream.listen(
-    (s) {
-      Expect.equals(11, s.length);
-      Expect.equals(new String.fromCharCodes([0x01]), s[0]);
-      Expect.equals(new String.fromCharCodes([0x7f]), s[1]);
-      Expect.equals(new String.fromCharCodes([0x80]), s[2]);
-      Expect.equals(new String.fromCharCodes([0x7ff]), s[3]);
-      Expect.equals(new String.fromCharCodes([0x800]), s[4]);
-      Expect.equals(new String.fromCharCodes([0xffff]), s[5]);
-      Expect.equals(new String.fromCharCodes([0xffff]), s[5]);
-
-      // Surrogate pair for U+1D11E.
-      Expect.equals(new String.fromCharCodes([0xd834, 0xdd1e]),
-                    s.substring(6, 8));
-
-      Expect.equals(new String.fromCharCodes(
-          [UNICODE_REPLACEMENT_CHARACTER_CODEPOINT,
-           UNICODE_REPLACEMENT_CHARACTER_CODEPOINT,
-           UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]),
-          s.substring(8, 11));
-    });
-}
-
-void testLatin1() {
-  List<int> data = [0x01,
-                    0x7f,
-                    0x44, 0x61, 0x72, 0x74,
-                    0x80,
-                    0xff,
-                    0x100, -0x1, -0xff];
-  var controller = new StreamController(sync: true);
-  controller.add(data);
-  controller.close();
-  var stream = controller.stream
-    .transform(new StringDecoder(Encoding.ISO_8859_1));
-  stream.listen((s) {
-    Expect.equals(11, s.length);
-    Expect.equals(new String.fromCharCodes([0x01]), s[0]);
-    Expect.equals(new String.fromCharCodes([0x7f]), s[1]);
-    Expect.equals("Dart", s.substring(2, 6));
-    Expect.equals(new String.fromCharCodes([0x80]), s[6]);
-    Expect.equals(new String.fromCharCodes([0xff]), s[7]);
-    Expect.equals('???', s.substring(8, 11));
-  });
-}
-
-void testAscii() {
-  List<int> data = [0x01,
-                    0x44, 0x61, 0x72, 0x74,
-                    0x7f,
-                    0xf4, 0x100, -0x1, -0xff];
-  var controller = new StreamController(sync: true);
-  controller.add(data);
-  controller.close();
-  var stream = controller.stream
-    .transform(new StringDecoder(Encoding.ASCII));
-  stream.listen((s) {
-    Expect.equals(10, s.length);
-    Expect.equals(new String.fromCharCodes([0x01]), s[0]);
-    Expect.equals("Dart", s.substring(1, 5));
-    Expect.equals(new String.fromCharCodes([0x7f]), s[5]);
-    Expect.equals('????', s.substring(6, 10));
-  });
-}
-
-void testReadLine1() {
-  var controller = new StreamController(sync: true);
-  var stream = controller.stream
-      .transform(new StringDecoder())
-      .transform(new LineSplitter());
-
-  var stage = 0;
-
-  void stringData(line) {
-    Expect.equals(stage, 0);
-    Expect.equals("Line", line);
-    stage++;
-  }
-
-  void streamClosed() {
-    Expect.equals(1, stage);
-  }
-
-  stream.listen(
-      stringData,
-      onDone: streamClosed);
-
-  // Note: codeUnits is fine. Text is ASCII.
-  controller.add("Line".codeUnits);
-  controller.close();
-  Expect.equals(1, stage);
-}
-
-void testReadLine2() {
-  var controller = new StreamController(sync: true);
-
-  var stream = controller.stream
-    .transform(new StringDecoder())
-    .transform(new LineSplitter());
-
-  var expectedLines = ['Line1', 'Line2','Line3', 'Line4',
-                       '', '', '', '', '', '',
-                       'Line5', 'Line6'];
-
-  var index = 0;
-
-  stream.listen((line) {
-    Expect.equals(expectedLines[index++], line);
-  });
-
-  // Note: codeUnits is fine. Text is ASCII.
-  controller.add("Line1\nLine2\r\nLine3\rLi".codeUnits);
-  controller.add("ne4\n".codeUnits);
-  controller.add("\n\n\r\n\r\n\r\r".codeUnits);
-  controller.add("Line5\r".codeUnits);
-  controller.add("\nLine6\n".codeUnits);
-  controller.close();
-  Expect.equals(expectedLines.length, index);
-}
-
-class TestException implements Exception {
-  TestException();
-}
-
-void testErrorHandler() {
-  var controller = new StreamController(sync: true);
-  var errors = 0;
-  var stream = controller.stream
-    .transform(new StringDecoder())
-    .transform(new LineSplitter());
-  stream.listen(
-      (_) {},
-      onDone: () {
-        Expect.equals(1, errors);
-      },
-      onError: (error) {
-        errors++;
-        Expect.isTrue(error is TestException);
-      });
-  controller.addError(new TestException());
-  controller.close();
-}
-
-void testLatin1EncoderError() {
-  List<int> data = [0x01,
-                    0x7f,
-                    0x44, 0x61, 0x72, 0x74,
-                    0x80,
-                    0xff,
-                    0x100];
-  var controller = new StreamController(sync: true);
-  controller.add(new String.fromCharCodes(data));
-  controller.close();
-  var stream = controller.stream
-    .transform(new StringEncoder(Encoding.ISO_8859_1));
-  stream.listen(
-    (s) {
-      Expect.fail("data not expected");
-    },
-    onError: (error) {
-      Expect.isTrue(error is FormatException);
-    });
-
-}
diff --git a/tests/standalone/io/web_socket_protocol_processor_test.dart b/tests/standalone/io/web_socket_protocol_processor_test.dart
index 4d90d73..4354ab0 100644
--- a/tests/standalone/io/web_socket_protocol_processor_test.dart
+++ b/tests/standalone/io/web_socket_protocol_processor_test.dart
@@ -3,7 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
-import "dart:utf";
+import "dart:convert";
 import "dart:math";
 import "dart:async";
 import "dart:collection";
@@ -41,7 +41,7 @@
 
   void onMessageData(buffer) {
     if (buffer is String) {
-      buffer = _encodeString(buffer);
+      buffer = UTF8.encode(buffer);
     }
     Expect.listEquals(expectedMessage, buffer);
     messageCount++;
diff --git a/tests/standalone/vmservice/test_helper.dart b/tests/standalone/vmservice/test_helper.dart
index d199d05..f70e0f0 100644
--- a/tests/standalone/vmservice/test_helper.dart
+++ b/tests/standalone/vmservice/test_helper.dart
@@ -97,7 +97,7 @@
       var portNumber;
       var blank;
       var first = true;
-      process.stdout.transform(new StringDecoder())
+      process.stdout.transform(UTF8.decoder)
                     .transform(new LineSplitter()).listen((line) {
         if (line.startsWith('VmService listening on port ')) {
           RegExp portExp = new RegExp(r"\d+");
@@ -116,7 +116,7 @@
         }
         print(line);
       });
-      process.stderr.transform(new StringDecoder())
+      process.stderr.transform(UTF8.decoder)
                     .transform(new LineSplitter()).listen((line) {
         print(line);
       });
diff --git a/tools/VERSION b/tools/VERSION
index 5018971..d90d5d2 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -1,4 +1,4 @@
 MAJOR 0
 MINOR 6
 BUILD 21
-PATCH 2
+PATCH 3
diff --git a/tools/coverage.dart b/tools/coverage.dart
index 350019d..37bb2bf 100644
--- a/tools/coverage.dart
+++ b/tools/coverage.dart
@@ -214,7 +214,7 @@
 
   Debugger(this.targetProcess) {
     var stdoutStringStream = targetProcess.stdout
-        .transform(new StringDecoder())
+        .transform(UTF8.decoder)
         .transform(new LineSplitter());
     stdoutStringStream.listen((line) {
       if (showDebuggeeOutput) {
@@ -231,7 +231,7 @@
     });
 
     var stderrStringStream = targetProcess.stderr
-        .transform(new StringDecoder())
+        .transform(UTF8.decoder)
         .transform(new LineSplitter());
     stderrStringStream.listen((line) {
       if (showDebuggeeOutput) {
@@ -372,7 +372,7 @@
     Socket.connect("127.0.0.1", portNumber).then((s) {
       socket = s;
       socket.setOption(SocketOption.TCP_NODELAY, true);
-      var stringStream = socket.transform(new StringDecoder());
+      var stringStream = socket.transform(UTF8.decoder);
       stringStream.listen(
           (str) {
             try {
diff --git a/tools/ddbg.dart b/tools/ddbg.dart
index 18673a6..132be10 100644
--- a/tools/ddbg.dart
+++ b/tools/ddbg.dart
@@ -590,7 +590,7 @@
   Socket.connect("127.0.0.1", 5858).then((s) {
     vmSock = s;
     vmSock.setOption(SocketOption.TCP_NODELAY, true);
-    var stringStream = vmSock.transform(new StringDecoder());
+    var stringStream = vmSock.transform(UTF8.decoder);
     vmSubscription = stringStream.listen(
         (String data) {
           processVmData(data);
@@ -604,7 +604,7 @@
           // TODO(floitsch): do we want to print the stack trace?
           quitShell();
         });
-    stdinSubscription = stdin.transform(new StringDecoder())
+    stdinSubscription = stdin.transform(UTF8.decoder)
                              .transform(new LineTransformer())
                              .listen((String line) => processCommand(line));
   });
diff --git a/utils/testrunner/layout_test_controller.dart b/utils/testrunner/layout_test_controller.dart
index 27cd1cb..31a35cf 100644
--- a/utils/testrunner/layout_test_controller.dart
+++ b/utils/testrunner/layout_test_controller.dart
@@ -168,7 +168,7 @@
 void _pipeStream(Stream stream, List<String> destination,
                  Function outputMonitor) {
   stream
-      .transform(new StringDecoder())
+      .transform(UTF8.decoder)
       .transform(new LineTransformer())
       .listen((String line) {
         if (outputMonitor != null) {
diff --git a/utils/testrunner/pipeline_utils.dart b/utils/testrunner/pipeline_utils.dart
index 72c0164..38ed392 100644
--- a/utils/testrunner/pipeline_utils.dart
+++ b/utils/testrunner/pipeline_utils.dart
@@ -101,7 +101,7 @@
 Future _pipeStream(Stream stream, List<String> destination,
                  Function outputMonitor) {
   return stream
-    .transform(new StringDecoder())
+    .transform(UTF8.decoder)
     .transform(new LineTransformer())
     .listen((String line) {
       if (config["immediate"] && line.startsWith('###')) {
diff --git a/utils/tests/testrunner/http_client_tests/http_client_test.dart b/utils/tests/testrunner/http_client_tests/http_client_test.dart
index 0016ce4..452c1ab 100644
--- a/utils/tests/testrunner/http_client_tests/http_client_test.dart
+++ b/utils/tests/testrunner/http_client_tests/http_client_test.dart
@@ -21,7 +21,7 @@
       // Process the response.
       expect(response.statusCode, code);
       var sb = new StringBuffer();
-      response.transform(new StringDecoder())
+      response.transform(UTF8.decoder)
        .listen((data) {
          sb.write(data);
       }, onDone: () {