`.offset()` takes CSS zoom into account

Description

Numerous jQuery UI widgets are not working correctly with CSS zoom, as reported in https://github.com/jquery/jquery-ui/issues/2292. The root cause is jQuery UI reliance on .offset() which returns final coordinates of the element, taking into account CSS transforms & CSS zoom - the jQuery UI issue is specifically about the latter.

I thought we should discuss the Core behavior.

Link to test case

• with CSS zoom: https://output.jsbin.com/zoyiwey/1
• with CSS transform / scale: https://output.jsbin.com/vuzupuk/1