Tweak a couple of method signatures for unittest methods so that they are more consistent.

pkg/utf/lib/src/list_range.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 utf.list_range;
 
 import 'dart:collection';
 
 /**
  * _ListRange in an internal type used to create a lightweight Interable on a
@@ skipping 30 matching lines @@
 
 /**
  * The ListRangeIterator provides more capabilities than a standard iterator,
  * including the ability to get the current position, count remaining items,
  * and move forward/backward within the iterator.
  */
 abstract class ListRangeIterator implements Iterator<int> {
   bool moveNext();
   int get current;
   int get position;
-  void backup([by]);
+  void backup([int by]);
   int get remaining;
-  void skip([count]);
+  void skip([int count]);
 }
 
 class _ListRangeIteratorImpl implements ListRangeIterator {
   final List<int> _source;
   int _offset;
   final int _end;
 
   _ListRangeIteratorImpl(this._source, int offset, this._end)
       : _offset = offset - 1;
 
   int get current => _source[_offset];
 
   bool moveNext() => ++_offset < _end;
 
   int get position => _offset;
 
   void backup([int by = 1]) {
     _offset -= by;
   }
 
   int get remaining => _end - _offset - 1;
 
   void skip([int count = 1]) {
     _offset += count;
   }
 }