[css-grid-2] Specify behaviour when a sub grids margin/border/padding is larger than the edge tracks maximum size #7072
Description
It appears that the abs-pos-002/3.html subgrid tests, as well as subgrid-mbp-overflow-001/2/3/4 all expect that the padding of the subgrid item is capped at the size of the edge track spanned by the subgrid item.
Minimised testcase showing capping in Gecko: https://jsfiddle.net/r3n0zt6v/
My reading of the spec suggests that we probably shouldn't do this, but there's a lot of tests requiring this behaviour.
It'd be good to clarify the intent here, and figure out how to adjust the tests.
I filed a WPT pull request for some of the tests, but the subgrid-mbp-overflow ones are significantly more involved - web-platform-tests/wpt#32611