css3 position

Currently the position:sticky element exclusively works when the all of general parents are overflow:visible. This is problematic a little whilst we use overflow:hidden trick for clearfix etc.

Testcase attached. Here is a simplesample, how is the layout broken when we change the overflow to visible, however sticky starts to work in that case. I detected, all of general parent-elements in the parent-path must be overflow: visible, which is weird a little. Any overflow:hidden in the parent-path kills the sticky.

ER: sync somehow the spec to allow sticky subcontainers inside a overflow:hidden general parent.

testcase: https://jsfiddle.net/utasir/rmmkxq62/11/