[Compositing] Which non-default behaviors create stacking contexts?

https://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html#csscompositingrules_CSS
says:

  # The application of non-default blending or compositing to an
  # element formatted with the CSS box model must also establishe a
  # stacking context the same way that CSS ‘opacity’ does.

This doesn't defined which properties count for "non-default
blending or compositing".  It needs to do so; the spec basically
isn't even understandable without knowing which properties this is
talking about.  (In particular, is it referring to just
mix-composite and mix-blend-mode, or also to some or all of
isolation, knock-out, background-composite, or
background-blend-mode?)

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                           http://www.mozilla.org/   𝄂