Bug 1341372 - Part 2: Support has_css_transitions.

Add one FFI to check if there is any transition in CSSTransitionCollection.
This will be used to check if we need to update transition and if we
should compute the after-change style.

MozReview-Commit-ID: 6HpVAtrx6Rc

components/script/layout_wrapper.rs

@@ -468,6 +468,10 @@ impl<'le> TElement for ServoLayoutElement<'le> {
     fn has_css_animations(&self, _pseudo: Option<&PseudoElement>) -> bool {
         panic!("this should be only called on gecko");
     }
+
+    fn has_css_transitions(&self, _pseudo: Option<&PseudoElement>) -> bool {
+        panic!("this should be only called on gecko");
+    }
 }
 
 impl<'le> PartialEq for ServoLayoutElement<'le> {

components/style/dom.rs

@@ -472,6 +472,9 @@ pub trait TElement : Eq + PartialEq + Debug + Hash + Sized + Copy + Clone +
     /// Returns true if the element has a CSS animation.
     fn has_css_animations(&self, _pseudo: Option<&PseudoElement>) -> bool;
 
+    /// Returns true if the element has a CSS transition.
+    fn has_css_transitions(&self, _pseudo: Option<&PseudoElement>) -> bool;
+
     /// Returns true if the element has animation restyle hints.
     fn has_animation_restyle_hints(&self) -> bool {
         let data = match self.borrow_data() {

components/style/gecko/wrapper.rs

@@ -34,6 +34,7 @@ use gecko_bindings::bindings::{Gecko_SetNodeFlags, Gecko_UnsetNodeFlags};
 use gecko_bindings::bindings::Gecko_ClassOrClassList;
 use gecko_bindings::bindings::Gecko_ElementHasAnimations;
 use gecko_bindings::bindings::Gecko_ElementHasCSSAnimations;
+use gecko_bindings::bindings::Gecko_ElementHasCSSTransitions;
 use gecko_bindings::bindings::Gecko_GetAnimationRule;
 use gecko_bindings::bindings::Gecko_GetExtraContentStyleDeclarations;
 use gecko_bindings::bindings::Gecko_GetHTMLPresentationAttrDeclarationBlock;
@@ -709,6 +710,11 @@ impl<'le> TElement for GeckoElement<'le> {
         let atom_ptr = PseudoElement::ns_atom_or_null_from_opt(pseudo);
         unsafe { Gecko_ElementHasCSSAnimations(self.0, atom_ptr) }
     }
+
+    fn has_css_transitions(&self, pseudo: Option<&PseudoElement>) -> bool {
+        let atom_ptr = PseudoElement::ns_atom_or_null_from_opt(pseudo);
+        unsafe { Gecko_ElementHasCSSTransitions(self.0, atom_ptr) }
+    }
 }
 
 impl<'le> PartialEq for GeckoElement<'le> {

components/style/gecko_bindings/bindings.rs

@@ -648,6 +648,11 @@ extern "C" {
                                          aPseudoTagOrNull: *mut nsIAtom)
      -> bool;
 }
+extern "C" {
+    pub fn Gecko_ElementHasCSSTransitions(aElement: RawGeckoElementBorrowed,
+                                          aPseudoTagOrNull: *mut nsIAtom)
+     -> bool;
+}
 extern "C" {
     pub fn Gecko_GetProgressFromComputedTiming(aComputedTiming:
                                                    RawGeckoComputedTimingBorrowed)