[css-grid] Avoid duplicated calls to resolution code

We were calling GridResolvedPosition::resolveGridPositionsFromStyle()
several times per item.

We can store the GridCoordinates in
LayoutGrid::populateExplicitGridAndOrderIterator()
and reuse them in the placement code.
Once LayoutGrid::placeItemsOnGrid() is over,
all the items will have a definite position in both axis.

No new tests, no change of behavior.

BUG=444011

GridResolvedPosition::resolveGridPositionsFromStyle

Review URL: https://codereview.chromium.org/1465153004

Cr-Commit-Position: refs/heads/master@{#361855}
1 file changed