Add chunked conversion to converters.

tests/lib/convert/chunked_conversion_utf83_test.dart

+// 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.
+
+// 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.
+
+library utf8_test;
+import "package:expect/expect.dart";
+import 'dart:convert';
+
+String decode(List<int> bytes) {
+  StringBuffer buffer = new StringBuffer();
+  ChunkedConversionSink stringSink =
+      new StringConversionSink.fromStringSink(buffer);
+  var byteSink = new Utf8Decoder().startChunkedConversion(stringSink);
+  bytes.forEach((byte) { byteSink.add([byte]); });
+  byteSink.close();
+  return buffer.toString();
+}
+
+String decodeAllowMalformed(List<int> bytes) {
+  StringBuffer buffer = new StringBuffer();
+  ChunkedConversionSink stringSink =
+      new StringConversionSink.fromStringSink(buffer);
+  var decoder = new Utf8Decoder(allowMalformed: true);
+  var byteSink = decoder.startChunkedConversion(stringSink);
+  bytes.forEach((byte) { byteSink.add([byte]); });
+  byteSink.close();
+  return buffer.toString();
+}
+
+main() {
+  // Test that chunked UTF8-decoder removes leading BOM.
+  Expect.equals("a", decode([0xEF, 0xBB, 0xBF, 0x61]));
+  Expect.equals("a", decodeAllowMalformed([0xEF, 0xBB, 0xBF, 0x61]));
+  Expect.equals("", decode([0xEF, 0xBB, 0xBF]));
+  Expect.equals("", decodeAllowMalformed([0xEF, 0xBB, 0xBF]));
+  Expect.equals("a\u{FEFF}", decode([0x61, 0xEF, 0xBB, 0xBF]));
+  Expect.equals("a\u{FEFF}", decodeAllowMalformed([0x61, 0xEF, 0xBB, 0xBF]));
+}