merge method

Implementation

WebViewStyle merge(WebViewStyle mergeWith) {
  return WebViewStyle(
    titleStyle: titleStyle ?? mergeWith.titleStyle,
    appBarColor: appBarColor ?? mergeWith.appBarColor,
    backIconColor: backIconColor ?? mergeWith.backIconColor,
    width: width ?? mergeWith.width,
    height: height ?? mergeWith.height,
    background: background ?? mergeWith.background,
    border: border ?? mergeWith.border,
    borderRadius: borderRadius ?? mergeWith.borderRadius,
    gradient: gradient ?? mergeWith.gradient,
  );
}