Move is_discrete from TransitionProperty to AnimatableLonghand

components/style/gecko/wrapper.rs

@@ -1130,14 +1130,14 @@ impl<'le> TElement for GeckoElement<'le> {
                                              -> bool {
         use properties::animated_properties::AnimatedProperty;
 
-        // We don't allow transitions on properties that are not interpolable.
-        if property.is_discrete() {
-            return false;
-        }
-
         // |property| should be an animatable longhand
         let animatable_longhand = AnimatableLonghand::from_transition_property(property).unwrap();
 
+        // We don't allow transitions on properties that are not interpolable.
+        if animatable_longhand.is_discrete() {
+            return false;
+        }
+
         if existing_transitions.contains_key(property) {
             // If there is an existing transition, update only if the end value differs.
             // If the end value has not changed, we should leave the currently running

components/style/properties/helpers/animated_properties.mako.rs

@@ -63,6 +63,18 @@ pub enum AnimatableLonghand {
 }
 
 impl AnimatableLonghand {
+    /// Returns true if this AnimatableLonghand is one of the discretely animatable properties.
+    pub fn is_discrete(&self) -> bool {
+        match *self {
+            % for prop in data.longhands:
+                % if prop.animation_value_type == "discrete":
+                    AnimatableLonghand::${prop.camel_case} => true,
+                % endif
+            % endfor
+            _ => false
+        }
+    }
+
     /// Converts from an nsCSSPropertyID. Returns None if nsCSSPropertyID is not an animatable
     /// longhand in Servo.
     #[cfg(feature = "gecko")]
@@ -224,19 +236,6 @@ impl TransitionProperty {
         }).map_err(|()| SelectorParseError::UnexpectedIdent(ident.into()).into())
     }
 
-    /// Returns true if this TransitionProperty is one of the discrete animatable properties and
-    /// this TransitionProperty should be a longhand property.
-    pub fn is_discrete(&self) -> bool {
-        match *self {
-            % for prop in data.longhands:
-                % if prop.animation_value_type == "discrete":
-                    TransitionProperty::${prop.camel_case} => true,
-                % endif
-            % endfor
-            _ => false
-        }
-    }
-
     /// Return animatable longhands of this shorthand TransitionProperty, except for "all".
     pub fn longhands(&self) -> &'static [TransitionProperty] {
         % for prop in data.shorthands_except_all():