public async Task<IJSCSGlue> Map(object from, object iadditional = null)
{
var res = await _Context.EvaluateOnUIContextAsync(() => InternalMap(from, iadditional));
await _Context.RunOnJavascriptContextAsync(() =>
{
res.ComputeJavascriptValue(_Context.WebView.Factory, _Cacher);
});
return res;
}