[css-grid] Fix grid container baseline alignment for orthogonal items

Grid container baseline was wrongly computed when done in reference
to an orthogonal item.
The fix is a simple change in LayoutGrid::FirstLineBoxBaseline()
to use LogicalTopForChild() so it takes into account grid container
and item writing modes.

BUG=943003
TEST=external/wpt/css/css-grid/alignment/grid-container-baseline-001.html

Change-Id: I86301933ac9ec30f6fee138cd49981bb79a4484e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1528183
Reviewed-by: Javier Fernandez <jfernandez@igalia.com>
Reviewed-by: Oriol Brufau <obrufau@igalia.com>
Commit-Queue: Manuel Rego <rego@igalia.com>
Cr-Commit-Position: refs/heads/master@{#641633}
2 files changed