Some more removals of dart:utf.

sdk/lib/_internal/compiler/implementation/tools/mini_parser.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 parser;
 
 import 'dart:io';
 import 'dart:typed_data';
 import 'dart:collection';
-import 'dart:utf';
 
 import '../elements/elements.dart';
 import '../scanner/scanner_implementation.dart';
 import '../scanner/scannerlib.dart';
 import '../tree/tree.dart';
 import '../util/characters.dart';
 import '../source_file.dart';
 import '../ssa/ssa.dart';
 
 import '../../compiler.dart' as api;
@@ skipping 284 matching lines @@
   set text(String newText) {
     throw "not supported";
   }
 }
 
 class Mock {
   const Mock();
   bool get useColors => true;
   internalError(message) { throw message.toString(); }
 }