The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e76547af4cb2b8b979b2b309f04c897cb6f74f79

commit e76547af4cb2b8b979b2b309f04c897cb6f74f79
Author: Sandra Sun <sunyunjia@chromium.org>
Date: Mon Mar 19 16:15:40 2018

scroll-snap-align should specify inline and block.

Currently, we parse the two values in scroll-snap-align for x and y.
However, according to the spec,
https://drafts.csswg.org/css-scroll-snap-1/#scroll-snap-align, the two
values specify the alignment in the inline axis and block axis. This
patch renames the two values and handles the vertical writing mode for
inline and block alignments.

Bug:  821645 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I78acff0df4698b3f9c0f7443e61e3bad75379b14
Reviewed-on: https://chromium-review.googlesource.com/967890
Commit-Queue: Sandra Sun <sunyunjia@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Reviewed-by: Ali Juma <ajuma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544055}
[modify] https://crrev.com/e76547af4cb2b8b979b2b309f04c897cb6f74f79/cc/input/scroll_snap_data.h
[add] https://crrev.com/e76547af4cb2b8b979b2b309f04c897cb6f74f79/third_party/WebKit/LayoutTests/external/wpt/css/css-scroll-snap/snap-inline-block.html
[modify] https://crrev.com/e76547af4cb2b8b979b2b309f04c897cb6f74f79/third_party/WebKit/Source/core/css/properties/ComputedStyleUtils.cpp
[modify] https://crrev.com/e76547af4cb2b8b979b2b309f04c897cb6f74f79/third_party/WebKit/Source/core/css/resolver/StyleBuilderConverter.cpp
[modify] https://crrev.com/e76547af4cb2b8b979b2b309f04c897cb6f74f79/third_party/WebKit/Source/core/page/scrolling/SnapCoordinator.cpp