Remove deprecated dart:utf library.

tools/testing/dart/utils.dart

 // 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 utils;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math' show min;
-import 'dart:utf' as utf;
+import 'dart:convert';
 
 part 'legacy_path.dart';
 
 class DebugLogger {
   static IOSink _sink;
 
   /**
    * If [path] was null, the DebugLogger will write messages to stdout.
    */
   static init(Path path, {append: false}) {
@@ skipping 89 matching lines @@
       }
     }
     if (found) {
       return i;
     }
   }
   return -1;
 }
 
 List<int> encodeUtf8(String string) {
-  return utf.encodeUtf8(string);
+  return UTF8.encode(string);
 }
 
 // TODO(kustermann,ricow): As soon we have a debug log we should log
 // invalid utf8-encoded input to the log.
 // Currently invalid bytes will be replaced by a replacement character.
 String decodeUtf8(List<int> bytes) {
-  return utf.decodeUtf8(bytes);
+  return UTF8.decode(bytes, allowMalformed: true);
 }
 
 class Locations {
   static String getDartiumLocation(Map globalConfiguration) {
     var dartium = globalConfiguration['dartium'];
     if (dartium != null && dartium != '') {
       return dartium;
     }
     if (Platform.operatingSystem == 'macos') {
       return new Path('client/tests/dartium/Chromium.app/Contents/'
@@ skipping 24 matching lines @@
 
 class UniqueObject {
   static int _nextId = 1;
   final int _hashCode;
 
   int get hashCode => _hashCode;
   operator==(other) => other is UniqueObject && _hashCode == other._hashCode;
 
   UniqueObject() : _hashCode = ++_nextId;
 }