The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0e13e93c4d942813878cf8f867e9a08e56e0547d

commit 0e13e93c4d942813878cf8f867e9a08e56e0547d
Author: Rune Lillesveen <futhark@chromium.org>
Date: Thu Jun 21 10:04:59 2018

Don't clear non-layout-object style for PseudoElements.

They are only used for storing an extra ComputedStyle for
display:contents pseudo elements as the ComputedStyle for rendering uses
a display:inline with only properties inherited for the parent element.

Bug:  854563 
Change-Id: I4dd3d99b0dee0b538645d005b36347b469799244
Reviewed-on: https://chromium-review.googlesource.com/1107802
Reviewed-by: Anders Ruud <andruud@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569204}
[modify] https://crrev.com/0e13e93c4d942813878cf8f867e9a08e56e0547d/third_party/WebKit/LayoutTests/external/wpt/css/cssom/getComputedStyle-pseudo-expected.txt
[modify] https://crrev.com/0e13e93c4d942813878cf8f867e9a08e56e0547d/third_party/WebKit/LayoutTests/external/wpt/css/cssom/getComputedStyle-pseudo.html
[modify] https://crrev.com/0e13e93c4d942813878cf8f867e9a08e56e0547d/third_party/blink/renderer/core/dom/element.cc