anchor.diff:  
     @override
     void setContents(Source source, String contents) {
  -    _recentTasks.clear();
  -    _reportedLoop = false;
       String originalContents = _contentCache.setContents(source, contents);
       if (contents != null) {
         if (contents != originalContents) {
  
positive.code:       }
      }
      _removeFromPartsUsingMap(oldPartMap);
      _recentTasks.clear();
      _reportedLoop = false;
    }
  
    /**
  
negative.code: 
    @override
    void setChangedContents(Source source, String contents, int offset, int oldLength, int newLength) {
      String originalContents = _contentCache.setContents(source, contents);
      if (contents != null) {
        if (contents != originalContents) {
  