The deeply nested links inside the div are our test subjects. The two functions,
getPageOffsetLeft, and getPageOffsetLeft_Iterative
calculate the distance of each header from the left side of the page.
getPageOffsetLeft calls itself recursively, passing the el param's
offsetParent to itsself.
getPageOffsetLeft_Iterative achieves the same result in an empty for loop.
In the alert box, distance should be always the same. Look for a difference in the value for time in ms (lower number is faster).