[anchor-position] OOF anchors in multicol

OOF in multicol is laid out when the multicol container is
laid out. Since at that point, all column boxes are already
laid out, |NGOutOfFlowLayoutPart| re-creates the column boxes
and use |NGContainerFragmentBuilder::ReplaceChild| to replace
it.

The |ReplaceChild| doesn't go though all propagation code in
|AddChild|, therefore misses propagating anchors of the OOF
themselves. This patch fixes this by propagating anchors
explicitly in |NGOutOfFlowLayoutPart|.

Propagating descendant anchors could stay in
|PropagateOOFPositionedInfo|, but this patch moves it to the
new |PropagateChildAnchors| function as it is easier to read
how anchors are propagated.

Bug: 1309178
Change-Id: I890e7045c15281a57bba41f0e8907f7d608d2e29
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3856814


Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1040243}