GitLab

BlockPainter::PaintChild() calls LayoutBox::FlipForWritingModeForChild()
which subtracts X() twice, so that child painter can add flipped block
physical offset. Because LayoutNG does not apply flipped block to its
Offset(), this resuts in incorrect paint offsets.

I think ideally paint should be able to handle without flipped block
throughout all painters, but I don't have enough knowledge to switch
to, or to add, such a mode to all painters at this point.

This patch matches NGBoxFragmentPainter's semantics to existing
painters for flipped block physical coordinate.

~120 tests pass, ~10 new failures, but remaining failures indicate
that paint offset needs more fixes. The semantics for floats, abspos,
tables, etc. are not clear yet to me.

Bug: 714962
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_layout_ng;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I35857fff030452dc618a529a5c45169e6fac378b
Reviewed-on: https://chromium-review.googlesource.com/966047
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Aleks Totic <atotic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543929}