Replace old utf8 decoder with new one.

tests/lib/convert/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.
+
+library utf8_test;
+import "package:expect/expect.dart";
+import 'dart:codec';
+import 'dart:convert';
+
+main() {
+  // Test that UTF8-decoder removes leading BOM.
+  Expect.equals("a", UTF8.decode([0xEF, 0xBB, 0xBF, 0x61]));
+  Expect.equals("a", UTF8.decoder.convert([0xEF, 0xBB, 0xBF, 0x61]));
+  Expect.equals("a", new Utf8Decoder().convert([0xEF, 0xBB, 0xBF, 0x61]));
+  Expect.equals("a",
+                UTF8.decode([0xEF, 0xBB, 0xBF, 0x61], allowMalformed: true));
+  Expect.equals("a", new Utf8Codec(allowMalformed: true)
+                         .decode([0xEF, 0xBB, 0xBF, 0x61]));
+  Expect.equals("a", new Utf8Codec(allowMalformed: true)
+                         .decoder.convert([0xEF, 0xBB, 0xBF, 0x61]));
+  Expect.equals("a", new Utf8Decoder(allowMalformed: true)
+                         .convert([0xEF, 0xBB, 0xBF, 0x61]));
+  Expect.equals("", UTF8.decode([0xEF, 0xBB, 0xBF]));
+  Expect.equals("", UTF8.decoder.convert([0xEF, 0xBB, 0xBF]));
+  Expect.equals("", new Utf8Decoder().convert([0xEF, 0xBB, 0xBF]));
+  Expect.equals("",
+                UTF8.decode([0xEF, 0xBB, 0xBF], allowMalformed: true));
+  Expect.equals("", new Utf8Codec(allowMalformed: true)
+                         .decode([0xEF, 0xBB, 0xBF]));
+  Expect.equals("", new Utf8Codec(allowMalformed: true)
+                         .decoder.convert([0xEF, 0xBB, 0xBF]));
+  Expect.equals("", new Utf8Decoder(allowMalformed: true)
+                         .convert([0xEF, 0xBB, 0xBF]));
+  Expect.equals("a\u{FEFF}", UTF8.decode([0x61, 0xEF, 0xBB, 0xBF]));
+  Expect.equals("a\u{FEFF}", UTF8.decoder.convert([0x61, 0xEF, 0xBB, 0xBF]));
+  Expect.equals("a\u{FEFF}",
+                new Utf8Decoder().convert([0x61, 0xEF, 0xBB, 0xBF]));
+  Expect.equals("a\u{FEFF}",
+                UTF8.decode([0x61, 0xEF, 0xBB, 0xBF], allowMalformed: true));
+  Expect.equals("a\u{FEFF}", new Utf8Codec(allowMalformed: true)
+                         .decode([0x61, 0xEF, 0xBB, 0xBF]));
+  Expect.equals("a\u{FEFF}", new Utf8Codec(allowMalformed: true)
+                         .decoder.convert([0x61, 0xEF, 0xBB, 0xBF]));
+  Expect.equals("a\u{FEFF}", new Utf8Decoder(allowMalformed: true)
+                         .convert([0x61, 0xEF, 0xBB, 0xBF]));
+}