Element.prototype.containsNode

@Description: Determines if this element is within another
@File: Element/prototype/isWithin.js
@Author: Paul Visco
@Version: 0.1 5-21-09 06-03-09
@Param: b The other element to determine if this element is within
@Return: returns boolean If element b is within this element
@Example:

$('#my_element').isWithin('#another_element');