[css-grid] 'grid-auto-flow' property

[mrego]

Grid items that aren’t explicitly placed are automatically placed into an unoccupied space in the grid container. The 'grid-auto-flow' property controls the direction in which the search for unoccupied space takes place, and whether rows or columns are added as needed to accommodate the content.
More info: http://www.w3.org/TR/css-grid-1/#grid-auto-flow-property

Note: The definitive values for this property are still under discussion in the CSS WG.

[mrego]

It seems that the values for this property are definite now: [ row | column ] || dense

[wpt-issue-mover]

This issue has been moved to web-platform-tests/wpt#5440; please continue all discussion there.