Use the new Uint8Buffer.addAll start and end params.

lib/src/percent/decoder.dart

 // Copyright (c) 2015, 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 convert.percent.decoder;
 
 import 'dart:convert';
 
 import 'package:charcode/ascii.dart';
 import 'package:typed_data/typed_data.dart';
@@ skipping 181 matching lines @@
     var codeUnit = codeUnits[i];
     if (codeUnits[i] != $percent) {
       codeUnitOr |= codeUnit;
       continue;
     }
 
     // We found a %. The slice from `sliceStart` to `i` represents characters
     // than can be copied to the buffer as-is.
     if (i > sliceStart) {
       _checkForInvalidCodeUnit(codeUnitOr, codeUnits, sliceStart, i);
-      buffer.addAll(codeUnits.getRange(sliceStart, i));
+      buffer.addAll(codeUnits, sliceStart, i);
     }
 
     // Now decode the percent-encoded byte and add it as well.
     i++;
     if (i >= end) return _lastPercent;
 
     var firstDigit = digitForCodeUnit(codeUnits, i);
     i++;
     if (i >= end) return 16 * firstDigit;
 
     var secondDigit = digitForCodeUnit(codeUnits, i);
     buffer.add(16 * firstDigit + secondDigit);
 
     // The next iteration will look for non-% characters again.
     sliceStart = i + 1;
   }
 
   if (end > sliceStart) {
     _checkForInvalidCodeUnit(codeUnitOr, codeUnits, sliceStart, end);
     if (start == sliceStart) {
       buffer.addAll(codeUnits);
     } else {
-      buffer.addAll(codeUnits.getRange(sliceStart, end));
+      buffer.addAll(codeUnits, sliceStart, end);
     }
   }
 
   return null;
 }
 
 void _checkForInvalidCodeUnit(int codeUnitOr, List<int> codeUnits, int start,
     int end) {
   if (codeUnitOr >= 0 && codeUnitOr <= 0x7f) return;
 
   for (var i = start; i < end; i++) {
     var codeUnit = codeUnits[i];
     if (codeUnit >= 0 && codeUnit <= 0x7f) continue;
     throw new FormatException(
         "Non-ASCII code unit "
             "U+${codeUnit.toRadixString(16).padLeft(4, '0')}",
         codeUnits, i);
   }
 }