Agenda for Dec 17 grid-lanes breakout

1. [css-grid-3][masonry] item-flow row vs. column in masonry layouts
https://github.com/w3c/csswg-drafts/issues/12803#issuecomment-3643945412

2. [css-grid-3][masonry] Adjustments/additions to grid shorthanding
https://github.com/w3c/csswg-drafts/issues/12023

3. [css-grid-3][masonry] Clarify what mixing subgridded items with automatic and definite grid position does
https://github.com/w3c/csswg-drafts/issues/10926

4. [css-grid-3] Make align-self/justify-self align including adjacent extra space
https://github.com/w3c/csswg-drafts/issues/10275

5. [css-grid-3][masonry] Effect of negative bottom margins on running position + dense-packing
https://github.com/w3c/csswg-drafts/issues/13164

6. [css-grid-3][masonry] Handling negative margins and dense packing for baseline calculation in the masonry axis
https://github.com/w3c/csswg-drafts/issues/13165