From c6cdaaf1cfb430ff5769770915be9a4591f7a096 Mon Sep 17 00:00:00 2001
From: Boris Chiou <boris.chiou@gmail.com>
Date: Fri, 2 Aug 2019 20:12:40 +0000
Subject: [PATCH] style: Make offset-anchor animatable.

Per the spec issue, https://github.com/w3c/csswg-drafts/issues/3482,
we update the wpt to keep the percentage in `calc()` for `offset-anchor`.

Differential Revision: https://phabricator.services.mozilla.com/D39552
---
 components/style/properties/longhands/box.mako.rs | 2 +-
 components/style/values/generics/position.rs      | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/components/style/properties/longhands/box.mako.rs b/components/style/properties/longhands/box.mako.rs
index 3dd1e419b526..cc464740e2e2 100644
--- a/components/style/properties/longhands/box.mako.rs
+++ b/components/style/properties/longhands/box.mako.rs
@@ -427,7 +427,7 @@ ${helpers.predefined_type(
     "PositionOrAuto",
     "computed::PositionOrAuto::auto()",
     engines="gecko",
-    animation_value_type="none",
+    animation_value_type="ComputedValue",
     gecko_pref="layout.css.motion-path.enabled",
     spec="https://drafts.fxtf.org/motion-1/#offset-anchor-property",
     servo_restyle_damage="reflow_out_of_flow",
diff --git a/components/style/values/generics/position.rs b/components/style/values/generics/position.rs
index 41ccf8a59531..2742dd879136 100644
--- a/components/style/values/generics/position.rs
+++ b/components/style/values/generics/position.rs
@@ -45,13 +45,16 @@ impl<H, V> Position<H, V> {
 /// This is used by <offset-anchor> for now.
 /// https://drafts.fxtf.org/motion-1/#offset-anchor-property
 #[derive(
+    Animate,
     Clone,
+    ComputeSquaredDistance,
     Copy,
     Debug,
     MallocSizeOf,
     Parse,
     PartialEq,
     SpecifiedValueInfo,
+    ToAnimatedZero,
     ToComputedValue,
     ToCss,
     ToResolvedValue,