Use the absolutely positioned box's own grid placement to resolve the
grid-area containing block rectangle instead of inheriting the nearest
in-flow grid item's area.
Keep the grid-specific static-position handling for axes with both
insets auto, but resolve mixed auto and explicit grid placement axes
against the augmented grid for direct children as well as descendants
inside grid items.
This fixes the imported abspos and alignment WPTs for values like
grid-row: 1 and grid-column: auto / 1 while keeping the reduced
descendant regressions passing.
