[css-pseudo] Move all ::marker style adjustments into StyleAdjuster

LayoutNGListItem was applying some style adjustments to markers, like
'white-space: pre' to preserve trailing spaces in outside markers.
But this was only affecting markers with 'content: normal', and the
changes weren't exposed in getComputedStyle().
This patch moves these adjustments into StyleAdjuster, so that all
markers are affected equally.



The test fails in legacy because the 'content' property is not supported
yet in ::marker.
There is a new failure in marker-supported-properties.html because now
'white-space' will compute to 'pre' in outside markers, even if you
specify a different value. But normal markers were already enforcing
'pre' at used value time anyways.

Change-Id: I6d8b8ec7fb26cb04402032924f87b2c3b8fdb9cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1985966
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Oriol Brufau <obrufau@igalia.com>
Cr-Commit-Position: refs/heads/master@{#728176}
8 files changed