UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36

Steps to reproduce the problem:
1. open an html document (window 0)
2. open a new window (window 1) and place it over window 0
3. verify that intersection observer still reports that content in window 0 is visible

What is the expected behavior?
Intersection observer should report content in an occluded window as not visible.

What went wrong?
On the desktop, Intersection Observer will report that an element is fully visible even though another window on the screen is preventing the user from seeing the element.  We propose that the calculations and event notifications of Intersection Observer include the layering and exposure of the window containing the web page.  This will improve the accuracy of viewability measurement.  It would also let web pages do things like pause animations when the presenting element is not visible.

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 58.0.3029.110  Channel: stable
OS Version: 
Flash Version: