anchor.diff:  
     Uri _cachedFallbackUri;
   
  -  FastUri(this._text, this._scheme, this._path, this._lastSlashIndex);
  +  FastUri._(this._cacheGeneration, this._text, this._scheme, this._path,
  +      this._lastSlashIndex);
   
     @override
     String get authority => '';
  
positive.code: 
    @override
    bool operator ==(other) {
      if (other is Uri) {
        if (other is FastUri) {
          return _text == other._text;
        }
        return _fallbackUri == other;
      }
      return false;
  
negative.code:     if (path.startsWith('//')) {
        path = path.substring(2);
      }
      return new FastUri._(
          _currentCacheGeneration, text, scheme, path, lastSlashIndex);
    }
  }
  