1 files changed, 38 insertions, 0 deletions
diff --git a/servo/components/style/values/specified/animation.rs b/servo/components/style/values/specified/animation.rs
index e7bbf26fb3..5a1f5003f3 100644
--- a/servo/components/style/values/specified/animation.rs
+++ b/servo/components/style/values/specified/animation.rs
@@ -112,6 +112,44 @@ impl TransitionProperty {
     }
 }
 
+/// A specified value for <transition-behavior-value>.
+///
+/// https://drafts.csswg.org/css-transitions-2/#transition-behavior-property
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    MallocSizeOf,
+    Parse,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(u8)]
+pub enum TransitionBehavior {
+    /// Transitions will not be started for discrete properties, only for interpolable properties.
+    Normal,
+    /// Transitions will be started for discrete properties as well as interpolable properties.
+    AllowDiscrete,
+}
+
+impl TransitionBehavior {
+    /// Return normal, the initial value.
+    #[inline]
+    pub fn normal() -> Self {
+        Self::Normal
+    }
+
+    /// Return true if it is normal.
+    #[inline]
+    pub fn is_normal(&self) -> bool {
+        matches!(*self, Self::Normal)
+    }
+}
+
 /// https://drafts.csswg.org/css-animations/#animation-iteration-count
 #[derive(Copy, Clone, Debug, MallocSizeOf, PartialEq, Parse, SpecifiedValueInfo, ToCss, ToShmem)]
 pub enum AnimationIterationCount {