Bug 1317209 - Part 3: Add TElement::get_animation_rule. r=heycam

We use TElement::get_animation_rule to get the animation rules from
Gecko side, which contain the interpolated values of the specific
element and the pseudo type.

components/style/dom.rs

@@ -248,6 +248,12 @@ pub trait TElement : PartialEq + Debug + Sized + Copy + Clone + ElementExt + Pre
     /// Get this element's style attribute.
     fn style_attribute(&self) -> Option<&Arc<RwLock<PropertyDeclarationBlock>>>;
 
+    /// Get this element's animation rule.
+    fn get_animation_rule(&self, _pseudo: Option<&PseudoElement>)
+                          -> Option<Arc<RwLock<PropertyDeclarationBlock>>> {
+        None
+    }
+
     /// Get this element's state, for non-tree-structural pseudos.
     fn get_state(&self) -> ElementState;
 

components/style/gecko/wrapper.rs

@@ -30,6 +30,7 @@ use gecko_bindings::bindings::{Gecko_IsLink, Gecko_IsRootElement, Gecko_MatchesE
 use gecko_bindings::bindings::{Gecko_IsUnvisitedLink, Gecko_IsVisitedLink, Gecko_Namespace};
 use gecko_bindings::bindings::{Gecko_SetNodeFlags, Gecko_UnsetNodeFlags};
 use gecko_bindings::bindings::Gecko_ClassOrClassList;
+use gecko_bindings::bindings::Gecko_GetAnimationRule;
 use gecko_bindings::bindings::Gecko_GetStyleContext;
 use gecko_bindings::structs;
 use gecko_bindings::structs::{RawGeckoElement, RawGeckoNode};
@@ -335,6 +336,12 @@ impl<'le> TElement for GeckoElement<'le> {
         declarations.map(|s| s.as_arc_opt()).unwrap_or(None)
     }
 
+    fn get_animation_rule(&self, pseudo: Option<&PseudoElement>)
+                          -> Option<Arc<RwLock<PropertyDeclarationBlock>>> {
+        let atom_ptr = pseudo.map(|p| p.as_atom().as_ptr()).unwrap_or(ptr::null_mut());
+        unsafe { Gecko_GetAnimationRule(self.0, atom_ptr) }.into_arc_opt()
+    }
+
     fn get_state(&self) -> ElementState {
         unsafe {
             ElementState::from_bits_truncate(Gecko_ElementState(self.0))

components/style/gecko_bindings/bindings.rs

@@ -501,6 +501,11 @@ extern "C" {
     pub fn Gecko_GetServoDeclarationBlock(element: RawGeckoElementBorrowed)
      -> RawServoDeclarationBlockStrongBorrowedOrNull;
 }
+extern "C" {
+    pub fn Gecko_GetAnimationRule(element: RawGeckoElementBorrowed,
+                                  aAtom: *mut nsIAtom)
+     -> RawServoDeclarationBlockStrong;
+}
 extern "C" {
     pub fn Gecko_Atomize(aString: *const ::std::os::raw::c_char, aLength: u32)
      -> *mut nsIAtom;