This seems to be what triggers the failure in LayoutTests/fast/block/positioning/trailing-space-test.html

I suddenly realized that I'm attempting to fix it myself. :)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cf8cefd730482dbc5f8d47c10932e0670ad77386

commit cf8cefd730482dbc5f8d47c10932e0670ad77386
Author: Morten Stenshorne <mstensho@chromium.org>
Date: Tue Feb 20 05:29:29 2018

[LayoutNG] Legacy static position for abspos inside inline.

An out-of-flow positioned box with hypothetically static (aka.
automatic) position needs to update its layer's static position also
when it's inside a (non-atomic) inline.

This fixes one layout test, but is also a step on the way to fixing
another one: fast/block/positioning/table-cell-static-position.html

Bug:  813525 
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: Ic4665a5371f2b2c306682f51e1d492205be6c719
Reviewed-on: https://chromium-review.googlesource.com/925601
Reviewed-by: Aleks Totic <atotic@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537720}
[modify] https://crrev.com/cf8cefd730482dbc5f8d47c10932e0670ad77386/third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG
[modify] https://crrev.com/cf8cefd730482dbc5f8d47c10932e0670ad77386/third_party/WebKit/Source/core/layout/ng/ng_block_node.cc