commit e970904c78038db4d51fd4f911d08c40d9c59030
author atotic <atotic@chromium.org> Sat Dec 03 02:51:30 2016
committer Commit bot <commit-bot@chromium.org> Sat Dec 03 02:54:12 2016
tree 9758ddcc25f7643a8f7783ada6f6c5bed7367f3a
parent 7a9d577b4d27f64420d5a6a0b3e5e6c2bdcbf6b5

Implement collection of out-of-flow descendants

Out-of-flow descendants need to know what their static position would
have been. This is because abspos spec defaults to static position if
TLBL are not specified.

Oof descendant's dimensions are not known during propagation, only
it's logical top/left offset. The offset is propagated as NGCorner,
which is a PhysicalOffset + vertex location (topLeft, bottomLeft, etc)

Next step will be positioning of oof descendants.

BUG=635619

Review-Url: https://codereview.chromium.org/2540653003
Cr-Commit-Position: refs/heads/master@{#436151}