Element.addMethods('iframe', {
document: function(element) {
element = $(element);
if (element.contentWindow)
return element.contentWindow.document;
else if (element.contentDocument)
return element.contentDocument;
else
return null;
},
$: function(element, frameElement) { 
element = $(element);
var frameDocument = element.document();
if (arguments.length > 2) {
for (var i = 1, frameElements = [], length = arguments.length; i < length; i++)
frameElements.push(element.$(arguments[i]));
return frameElements;
}
if (Object.isString(frameElement))
frameElement = frameDocument.getElementById(frameElement);
return frameElement || element;
}
});