Some more removals of dart:utf.

pkg/source_maps/lib/printer.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.
 
 /// Contains a code printer that generates code by recording the source maps.
 library source_maps.printer;
 
-import 'dart:utf' show stringToCodepoints;
 import 'builder.dart';
 import 'span.dart';
 
 const int _LF = 10;
 const int _CR = 13;
 
 /// A simple printer that keeps track of offset locations and records source
 /// maps locations.
 class Printer {
   final String filename;
@@ skipping 12 matching lines @@
   int _column = 0;
 
   Printer(this.filename);
 
   /// Add [str] contents to the output, tracking new lines to track correct
   /// positions for span locations. When [projectMarks] is true, this method
   /// adds a source map location on each new line, projecting that every new
   /// line in the target file (printed here) corresponds to a new line in the
   /// source file.
   void add(String str, {projectMarks: false}) {
-    var chars = stringToCodepoints(str);
+    var chars = str.runes.toList();
     var length = chars.length;
     for (int i = 0; i < length; i++) {
       var c = chars[i];
       if (c == _LF || (c == _CR && (i + 1 == length || chars[i + 1] != _LF))) {
         // Return not followed by line-feed is treated as a new line.
         _line++;
         _column = 0;
         if (projectMarks && _loc != null) {
           if (_loc is FixedLocation) {
             mark(new FixedLocation(0, _loc.sourceUrl, _loc.line + 1, 0));
@@ skipping 184 matching lines @@
       }
     }
   }
 }
 
 /// An item added to a [NestedPrinter].
 abstract class NestedItem {
   /// Write the contents of this item into [printer].
   void writeTo(Printer printer);
 }