Put computed values into AnimationValueMap instead of hashtable in gecko.

Before this patch, we store each computed values in a hashtable,
nsRefPtrHashtable<nsUint32HashKey, RawServoAnimationValue>, for all
KeyframeEffectReadOnly on an element, and convert the ServoAnimationValues of
the hashtable into an nsTArray<ServoAnimationValue*> and then convert
the ServoAnimationValues of the nsTArray into PropertyDeclarationBlock
in rust.  This way was really inefficient.
In this patch, we store the computed values into AnimationValueMap and
convert all AnimationValue in the map into PropertyDeclarationBlock
after EffectCompositor::GetAnimationRule.

components/style/gecko/wrapper.rs

@@ -46,6 +46,7 @@ use parking_lot::RwLock;
 use parser::ParserContextExtraData;
 use properties::{ComputedValues, parse_style_attribute};
 use properties::PropertyDeclarationBlock;
+use properties::animated_properties::AnimationValueMap;
 use rule_tree::CascadeLevel as ServoCascadeLevel;
 use selector_parser::{ElementExt, Snapshot};
 use selectors::Element;
@@ -403,6 +404,20 @@ fn selector_flags_to_node_flags(flags: ElementSelectorFlags) -> u32 {
     gecko_flags
 }
 
+fn get_animation_rule(element: &GeckoElement,
+                      pseudo: Option<&PseudoElement>,
+                      cascade_level: CascadeLevel)
+                      -> Option<Arc<RwLock<PropertyDeclarationBlock>>> {
+    let atom_ptr = PseudoElement::ns_atom_or_null_from_opt(pseudo);
+    let animation_values = Arc::new(RwLock::new(AnimationValueMap::new()));
+    if unsafe { Gecko_GetAnimationRule(element.0, atom_ptr, cascade_level,
+                                       HasArcFFI::arc_as_borrowed(&animation_values)) } {
+        Some(Arc::new(RwLock::new(PropertyDeclarationBlock::from_animation_value_map(&animation_values.read()))))
+    } else {
+        None
+    }
+}
+
 impl<'le> TElement for GeckoElement<'le> {
     type ConcreteNode = GeckoNode<'le>;
 
@@ -422,14 +437,12 @@ impl<'le> TElement for GeckoElement<'le> {
 
     fn get_animation_rule(&self, pseudo: Option<&PseudoElement>)
                           -> Option<Arc<RwLock<PropertyDeclarationBlock>>> {
-        let atom_ptr = PseudoElement::ns_atom_or_null_from_opt(pseudo);
-        unsafe { Gecko_GetAnimationRule(self.0, atom_ptr, CascadeLevel::Animations).into_arc_opt() }
+        get_animation_rule(self, pseudo, CascadeLevel::Animations)
     }
 
     fn get_transition_rule(&self, pseudo: Option<&PseudoElement>)
                            -> Option<Arc<RwLock<PropertyDeclarationBlock>>> {
-        let atom_ptr = PseudoElement::ns_atom_or_null_from_opt(pseudo);
-        unsafe { Gecko_GetAnimationRule(self.0, atom_ptr, CascadeLevel::Transitions).into_arc_opt() }
+        get_animation_rule(self, pseudo, CascadeLevel::Transitions)
     }
 
     fn get_state(&self) -> ElementState {

components/style/gecko_bindings/bindings.rs

@@ -582,8 +582,10 @@ extern "C" {
     pub fn Gecko_GetAnimationRule(aElement: RawGeckoElementBorrowed,
                                   aPseudoTag: *mut nsIAtom,
                                   aCascadeLevel:
-                                      EffectCompositor_CascadeLevel)
-     -> RawServoDeclarationBlockStrong;
+                                      EffectCompositor_CascadeLevel,
+                                  aAnimationValues:
+                                      RawServoAnimationValueMapBorrowed)
+     -> bool;
 }
 extern "C" {
     pub fn Gecko_StyleAnimationsEquals(arg1:
@@ -1496,6 +1498,13 @@ extern "C" {
                                            result:
                                                RawGeckoComputedKeyframeValuesListBorrowedMut);
 }
+extern "C" {
+    pub fn Servo_AnimationValueMap_Push(arg1:
+                                            RawServoAnimationValueMapBorrowed,
+                                        property: nsCSSPropertyID,
+                                        value:
+                                            RawServoAnimationValueBorrowed);
+}
 extern "C" {
     pub fn Servo_AnimationValues_Interpolate(from:
                                                  RawServoAnimationValueBorrowed,

components/style/gecko_bindings/structs_debug.rs

@@ -8214,9 +8214,6 @@ pub mod root {
         }
         #[repr(C)]
         #[derive(Debug, Copy, Clone)]
-        pub struct ServoAnimationRule([u8; 0]);
-        #[repr(C)]
-        #[derive(Debug, Copy, Clone)]
         pub struct AnimationPerformanceWarning([u8; 0]);
         pub type CSSPseudoClassTypeBase = u8;
         #[repr(u8)]

components/style/gecko_bindings/structs_release.rs

@@ -8026,9 +8026,6 @@ pub mod root {
         }
         #[repr(C)]
         #[derive(Debug, Copy, Clone)]
-        pub struct ServoAnimationRule([u8; 0]);
-        #[repr(C)]
-        #[derive(Debug, Copy, Clone)]
         pub struct AnimationPerformanceWarning([u8; 0]);
         pub type CSSPseudoClassTypeBase = u8;
         #[repr(u8)]