UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/601.4.4 (KHTML, like Gecko) Version/9.0.3 Safari/601.4.4

Steps to reproduce the problem:
1. Declare event handlers for on scroll and onresize 
2. if 200 from bottom of page, show alert
3. on a small (height) window with a long page, use a single quick swipe on a magic mouse so that the contents scrolls to the bottom - are it a fast one!

What is the expected behavior?
should show the alert

What went wrong?
the event appears to trigger before the scroll is finished but not at the end. This came about when trying to implement lazy-loading on images. Scroll to the bottom too fast using a single swipe on the magic mouse (and probably track pad) and the images at the bottom never show - move up/down slightly and they appear as expected. Works perfectly on Mac Safari

Did this work before? N/A 

Chrome version: 49.0.2623.87 (64-bit)  Channel: n/a
OS Version: OS X 10.11.3
Flash Version: Shockwave Flash 21.0 r0