Function: isWithin(domElement, domContainerElement)

Description: Checks if a DOM node is contained within the specified container element.

Returns: True if yes, False otherwise.

Note: If domContainerElement is not specified, it will default to document.body.

Example:

// Verify if a DOM node is present within document.body.
var isInBody = $A.isWithin(domElement);

// Verify if a DOM node is present within the specified container element.
var isWithin = $A.isWithin(domElement, parentContainerElement);