CSSWG has resolved  to change the ordering of scroll-snap-align property to be in "block inline" order. WebKit parsing logic appear to do "inline, block" order.
I have changed Chromium implementation to match the specification but it is now different from Safari.
The current usage of two value is low but as it grows the interop issue problem grows.
- My backward compat analysis suggested the risk is low 
- Relevant WPT test .
I tested this on Safari 12.0.1.
Created attachment 417539 [details]
Comment on attachment 417539 [details]
Please fix the failing test.
Created attachment 417604 [details]
Committed r271480: <https://trac.webkit.org/changeset/271480>
All reviewed patches have been landed. Closing bug and clearing flags on attachment 417604 [details].