[web] remove widget.render backward compatibility
there are very few widgets outside CW that used old render API and they
should have all been updated by now.
CubicWeb.require('ajax.js');
function removeBookmark(beid) {
d = asyncRemoteExec('delete_bookmark', beid);
d.addCallback(function(boxcontent) {
reloadComponent('bookmarks_box', '', 'boxes', 'bookmarks_box');
document.location.hash = '#header';
updateMessage(_("bookmark has been removed"));
});
}