anchor.diff:        fontSize: fontSize != null ? fontSize : this.fontSize,
         fontWeight: fontWeight != null ? fontWeight : this.fontWeight,
         fontStyle: fontStyle != null ? fontStyle : this.fontStyle,
  +      letterSpacing: letterSpacing != null ? letterSpacing : this.letterSpacing,
         textAlign: textAlign != null ? textAlign : this.textAlign,
         textBaseline: textBaseline != null ? textBaseline : this.textBaseline,
         height: height != null ? height : this.height,
  
positive.code:       fontWeight: fontWeight,
        fontStyle: fontStyle,
        fontFamily: fontFamily,
        fontSize: fontSize
      );
    }
  
  
negative.code:     value = 37 * value + fontSize.hashCode;
      value = 37 * value + fontWeight.hashCode;
      value = 37 * value + fontStyle.hashCode;
      value = 37 * value + letterSpacing.hashCode;
      value = 37 * value + textAlign.hashCode;
      value = 37 * value + textBaseline.hashCode;
      value = 37 * value + decoration.hashCode;
  