[LayoutNG] Adapt LayoutInline::LinesBoundingBox() to work with fragments

This patch makes |LayoutInline::LinesBoundingBox()| to work with LayoutNG by
utilizing |NGInlineFragmentIterator| to collect box fragments associated to
|LayoutInline|.

This patch also changes |ShouldCreateBoxFragment()| to return |true| for
producing box fragements for plain SPAN to avoid using "culled inline box",
which is collected by traversing descendants of layout tree.

Note: Exclude master.tryserver.chromium.linux:linux_layout_tests_layout_ng

Bug: 591099
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: Ia71db55d551a8ee8e5e36019ab94e7fb18479198
Reviewed-on: https://chromium-review.googlesource.com/768599
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521017}
2 files changed