[LayoutNG] Make <LI>'s line-height effective when list-style-type: none

Like legacy layout, in order to match other browsers when list-style-type
is none, pretend there's an invisible marker in <LI>.

Bug: 725277
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng
Change-Id: I35d3122f9a99a4262ee41236650ff41aa09ff53d
Reviewed-on: https://chromium-review.googlesource.com/1138044
Reviewed-by: Koji Ishii <kojii@chromium.org>
Commit-Queue: cathie chen <cathiechen@tencent.com>
Cr-Commit-Position: refs/heads/master@{#575526}
2 files changed