[css-contain] Clarify what happens when display: contents and contain: style are used together #7392
Description
Regarding https://drafts.csswg.org/css-contain/#containment-style:
The other types of containment have language like this:
If the element does not generate a principal box (as is the case with display values of contents or none), or its principal box is an internal table box other than table-cell, or an internal ruby box, or a non-atomic inline-level box, paint containment has no effect.
This means these types of containment have no affect when display: contents is used. In the case of contain: style this text isn't there. Should elements that have contain: style and display: contents establish a new style boundary? It seems that in Chrome it does, though perhaps with some bugs. In Gecko, this behavior might be a bit trickier to implement.