[LayoutNG] Fix orthogonal writing mode with abs/fixed descendants.

The current code was mixing up the block_estimate between
descendant/container writing modes. It keeps it now in the child's
writing mode.

BUG=635619

Review-Url: https://codereview.chromium.org/2727263003
Cr-Commit-Position: refs/heads/master@{#454517}
2 files changed