1302839 - [css-grid] optimize calculating grid-gap contribution to a particular span length

Status: NEW

(Core :: Layout: Grid, defect, P3)

Description

[Mats Palmgren (inactive)]

It occurred to me that this:

+    nscoord space = aAvailableSpace - mGridGap * (aRange.Extent() - 1);

which we added in bug 1299133, can be optimized by moving the latter term
one level up instead.  This code is in CollectGrowable, which is called for
each item, but the calling code does so in span order, i.e. all items with
span=2 is called in sequence, then span=3 etc, so we can calculate
"mGridGap * (aRange.Extent() - 1)" once for each span value rather
than for each item.  And reuse the same value for all the CollectGrowable
calls there.  And probably also subtract it directly before:
          if (space <= 0) {
            continue;
          }
so that we don't even need to call CollectGrowable in that case.