Drop AnimatedProperty for stylo.

set_list_style_type() for gecko needs an additional argument 'Device' [1], and
making list-style-type animtable makes AnimatedProperty::update() call the
set_list_style_type(). To avoid introducing the Device argument to the setter in
servo, this patch makes simply PropertyAnimation conditional build.
(Whereas in stylo, we don't use the setter for animation, we use clone_xx()
instead.)

[1] https://hg.mozilla.org/mozilla-central/file/1d042bcb2632/servo/components/style/properties/properties.mako.rs#l2667

components/style/context.rs

@@ -5,7 +5,7 @@
 //! The context within which style is calculated.
 
 #[cfg(feature = "servo")] use animation::Animation;
-use animation::PropertyAnimation;
+#[cfg(feature = "servo")] use animation::PropertyAnimation;
 use app_units::Au;
 use bloom::StyleBloom;
 use cache::LRUCache;
@@ -293,6 +293,7 @@ pub struct CurrentElementInfo {
     is_initial_style: bool,
     /// A Vec of possibly expired animations. Used only by Servo.
     #[allow(dead_code)]
+    #[cfg(feature = "servo")]
     pub possibly_expired_animations: Vec<PropertyAnimation>,
 }
 
@@ -668,6 +669,17 @@ impl<E: TElement> ThreadLocalStyleContext<E> {
         }
     }
 
+    #[cfg(feature = "gecko")]
+    /// Notes when the style system starts traversing an element.
+    pub fn begin_element(&mut self, element: E, data: &ElementData) {
+        debug_assert!(self.current_element_info.is_none());
+        self.current_element_info = Some(CurrentElementInfo {
+            element: element.as_node().opaque(),
+            is_initial_style: !data.has_styles(),
+        });
+    }
+
+    #[cfg(feature = "servo")]
     /// Notes when the style system starts traversing an element.
     pub fn begin_element(&mut self, element: E, data: &ElementData) {
         debug_assert!(self.current_element_info.is_none());

components/style/lib.rs

@@ -92,7 +92,7 @@ extern crate unicode_segmentation;
 #[macro_use]
 mod macros;
 
-pub mod animation;
+#[cfg(feature = "servo")] pub mod animation;
 pub mod applicable_declarations;
 #[allow(missing_docs)] // TODO.
 #[cfg(feature = "servo")] pub mod attr;

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

@@ -387,6 +387,7 @@ pub fn nscsspropertyid_is_transitionable(property: nsCSSPropertyID) -> bool {
 
 /// An animated property interpolation between two computed values for that
 /// property.
+#[cfg(feature = "servo")]
 #[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum AnimatedProperty {
@@ -404,6 +405,7 @@ pub enum AnimatedProperty {
     % endfor
 }
 
+#[cfg(feature = "servo")]
 impl AnimatedProperty {
     /// Get the name of this property.
     pub fn name(&self) -> &'static str {