docs: function extend(what, whit) {
  		Object.keys(whit).forEach(function(key) {
  			var def = whit[key];
  			if (what[key] === undefined) {
  				if (def.get && def.set) {
  					// TODO: look at element.dataset polyfill (iOS?)
  				} else {
  					what[key] = def;
  				}
  			}
  		});
  	}