GitLab

This gets more coverage on the paint portions and ensures these cases
get coverage in WPT. There was one converted test that looks like it
is not working correctly under LayoutNG block fragmentation so filed a
bug to fix that in follow up.

There are a couple of others (break-before and -after for children of
abs-pos elements, and some spanner tests) that don't match Chromium nor
Firefox currently - these need a bit more investigation.

Change-Id: I6d3bcb0c1de2835f990b95d04ad32175150609dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2525844
Commit-Queue: Daniel Libby <dlibby@microsoft.com>
Reviewed-by: Alison Maher <almaher@microsoft.com>
Reviewed-by: Benjamin Beaudry <benjamin.beaudry@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#826202}