1689773 - [wpt-sync] Sync PR 27408 - [LayoutNG] Fix order OOFs are added in

Status: RESOLVED INVALID

(Core :: Layout, task, P4)

Description

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 27408 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/27408
Details from upstream follow.

b'Alison Maher <[e-mail]>' wrote:

[LayoutNG] Fix order OOFs are added in

I was investigating whether we were handling break tokens correctly
for new columns added during OOF positioned layout. This ended up
looking correct as-is, but I ran into a couple of issues while
testing this.

1. We were getting the incorrect previous_break_token for columns
   in the presence of spanners. To fix this, look for the first
   non-spanner sibling for the previous break token.

2. We were adding OOFs to columns in an incorrect order. Instead of
   simply looking at IsFirstForNode(), we also have to look at the
   fragment index of existing children vs that of the OOF
   fragments being added to determine a consistent child order.

To efficiently handle to ordering problem, I've also slightly
updated how we are storing the OOF layout results to not only group them
by fragmentainer index, but also their by fragment indexes.

Bug: 1079031
Change-Id: Iaa7d5b19bc3ca101554f24a672989c6531abfce1

Reviewed-on: https://chromium-review.googlesource.com/2660716
WPT-Export-Revision: 807794aefb748fcce7cc93c4ef081b5f6326afb0