anchor.diff:      }
   
       var solution = new Solution(prefix);
  -    _tryChunkRuleValues(solution, prefix, prefix.column);
  +    _tryChunkRuleValues(solution, prefix);
   
       if (debug.traceSplitter) {
         debug.unindent();
  
positive.code: 
    /// Updates [solution] with the best rule value selection for the chunk
    /// immediately following [prefix].
    void _tryChunkRuleValues(Solution solution, LinePrefix prefix, int length) {
      // If we made it to the end, this prefix can be solved without splitting
      // any chunks.
      if (prefix.length == _chunks.length - 1) {
  
negative.code:       // We didn't split here, so add this chunk and its rule value to the
        // prefix and continue on to the next.
        var added = prefix.extend(_advancePrefix(prefix, value));
        _tryChunkRuleValues(solution, added);
      }
    }
  
  