Fix position:sticky on nested table parts

Bug: 702927
Change-Id: Ifeaa89a292e96bb66a26507ab85cf4e3a81d42c4
Reviewed-on: https://chromium-review.googlesource.com/786014
Commit-Queue: Robert Hogan <robhogan@gmail.com>
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520181}
3 files changed