From 82d7f2154d40899fa2fc0a85aba1de4d08d62aa8 Mon Sep 17 00:00:00 2001
From: Boris Chiou <boris.chiou@gmail.com>
Date: Mon, 13 Jun 2022 20:26:45 +0000
Subject: [PATCH] style: Hook named scroll timelines to animation-timeline

Basically, animation-timeline could be
1. auto
2. none
3. <timeline-name>

We extend the <timeline-name> to cover both @scroll-timeline rule and
scroll-timeline-name property. We check @scroll-timeline rule first. If
it doesn't exist, we check scroll-timeline-name of the element itself,
the previous silbings, and their ancestors.

Differential Revision: https://phabricator.services.mozilla.com/D146358
---
 components/style/values/specified/box.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/components/style/values/specified/box.rs b/components/style/values/specified/box.rs
index c9583c96235..0fbb030143e 100644
--- a/components/style/values/specified/box.rs
+++ b/components/style/values/specified/box.rs
@@ -815,9 +815,13 @@ fn is_default<T: Default + PartialEq>(value: &T) -> bool {
 pub enum AnimationTimeline {
     /// Use default timeline. The animation’s timeline is a DocumentTimeline.
     Auto,
-    /// The scroll-timeline name
+    /// The scroll-timeline name.
+    ///
+    /// Note: This could be the timeline name from @scroll-timeline rule, or scroll-timeline-name
+    /// from itself, its ancestors, or its previous siblings.
+    /// https://drafts.csswg.org/scroll-animations-1/rewrite#scroll-timelines-named
     Timeline(TimelineName),
-    /// The scroll() notation
+    /// The scroll() notation.
     /// https://drafts.csswg.org/scroll-animations-1/rewrite#scroll-notation
     #[css(function)]
     Scroll(