Introduce eRestyle_CSSAnimations.

RESTYLE_CSS_ANIMATIONS will be individually processed prior to other restyle
hints in a traversal.

components/style/data.rs

@@ -9,7 +9,7 @@
 use dom::TElement;
 use properties::ComputedValues;
 use properties::longhands::display::computed_value as display;
-use restyle_hints::{RESTYLE_DESCENDANTS, RESTYLE_LATER_SIBLINGS, RESTYLE_SELF, RestyleHint};
+use restyle_hints::{RESTYLE_CSS_ANIMATIONS, RESTYLE_DESCENDANTS, RESTYLE_LATER_SIBLINGS, RESTYLE_SELF, RestyleHint};
 use rule_tree::StrongRuleNode;
 use selector_parser::{PseudoElement, RestyleDamage, Snapshot};
 use std::collections::HashMap;
@@ -136,7 +136,12 @@ pub struct StoredRestyleHint(RestyleHint);
 impl StoredRestyleHint {
     /// Propagates this restyle hint to a child element.
     pub fn propagate(&self) -> Self {
-        StoredRestyleHint(if self.0.contains(RESTYLE_DESCENDANTS) {
+        // If we have RESTYLE_CSS_ANIMATIONS restyle hint, it means we are in the
+        // middle of an animation only restyle.  In that case, we don't need to
+        // propagate any restyle hints.
+        StoredRestyleHint(if self.0.contains(RESTYLE_CSS_ANIMATIONS) {
+            RestyleHint::empty()
+        } else if self.0.contains(RESTYLE_DESCENDANTS) {
             RESTYLE_SELF | RESTYLE_DESCENDANTS
         } else {
             RestyleHint::empty()
@@ -174,6 +179,16 @@ impl StoredRestyleHint {
     pub fn insert(&mut self, other: &Self) {
         self.0 |= other.0
     }
+
+    /// Remove animation restyle hint.
+    pub fn remove_animation_hint(&mut self) {
+        self.0.remove(RESTYLE_CSS_ANIMATIONS)
+    }
+
+    /// Returns true if the hint has animation-only restyle.
+    pub fn has_animation_hint(&self) -> bool {
+        self.0.contains(RESTYLE_CSS_ANIMATIONS)
+    }
 }
 
 impl Default for StoredRestyleHint {

components/style/matching.rs

@@ -17,7 +17,7 @@ use data::{ComputedStyle, ElementData, ElementStyles, RestyleData};
 use dom::{AnimationRules, SendElement, TElement, TNode};
 use properties::{CascadeFlags, ComputedValues, SHAREABLE, SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP, cascade};
 use properties::longhands::display::computed_value as display;
-use restyle_hints::{RESTYLE_STYLE_ATTRIBUTE, RestyleHint};
+use restyle_hints::{RESTYLE_STYLE_ATTRIBUTE, RESTYLE_CSS_ANIMATIONS, RestyleHint};
 use rule_tree::{CascadeLevel, RuleTree, StrongRuleNode};
 use selector_parser::{PseudoElement, RestyleDamage, SelectorImpl};
 use selectors::MatchAttr;
@@ -957,7 +957,8 @@ pub trait MatchMethods : TElement {
         use properties::PropertyDeclarationBlock;
         use shared_lock::Locked;
 
-        let primary_rules = &mut data.styles_mut().primary.rules;
+        let element_styles = &mut data.styles_mut();
+        let primary_rules = &mut element_styles.primary.rules;
         let mut rule_node_changed = false;
 
         {
@@ -972,7 +973,27 @@ pub trait MatchMethods : TElement {
                 }
             };
 
-            if hint.contains(RESTYLE_STYLE_ATTRIBUTE) {
+            // RESTYLE_CSS_ANIMATIONS is processed prior to other restyle hints
+            // in the name of animation-only traversal. Rest of restyle hints
+            // will be processed in a subsequent normal traversal.
+            if hint.contains(RESTYLE_CSS_ANIMATIONS) {
+                debug_assert!(context.shared.animation_only_restyle);
+
+                let animation_rule = self.get_animation_rule(None);
+                replace_rule_node(CascadeLevel::Animations,
+                                  animation_rule.as_ref(),
+                                  primary_rules);
+
+                let iter = element_styles.pseudos.iter_mut().filter(|&(p, _)|
+                    <Self as MatchAttr>::Impl::pseudo_is_before_or_after(p));
+                for (pseudo, ref mut computed) in iter {
+                    let animation_rule = self.get_animation_rule(Some(pseudo));
+                    let pseudo_rules = &mut computed.rules;
+                    replace_rule_node(CascadeLevel::Animations,
+                                      animation_rule.as_ref(),
+                                      pseudo_rules);
+                }
+            } else if hint.contains(RESTYLE_STYLE_ATTRIBUTE) {
                 let style_attribute = self.style_attribute();
                 replace_rule_node(CascadeLevel::StyleAttributeNormal,
                                   style_attribute,
@@ -980,6 +1001,7 @@ pub trait MatchMethods : TElement {
                 replace_rule_node(CascadeLevel::StyleAttributeImportant,
                                   style_attribute,
                                   primary_rules);
+                // The per-pseudo rule nodes never change in this path.
             }
         }
 

components/style/restyle_hints.rs

@@ -47,6 +47,11 @@ bitflags! {
         /// of their descendants.
         const RESTYLE_LATER_SIBLINGS = 0x08,
 
+        /// Replace the style data coming from CSS animations without updating
+        /// any other style data. This hint is only processed in animation-only
+        /// traversal which is prior to normal traversal.
+        const RESTYLE_CSS_ANIMATIONS = 0x20,
+
         /// Don't re-run selector-matching on the element, only the style
         /// attribute has changed, and this change didn't have any other
         /// dependencies.
@@ -81,6 +86,7 @@ pub fn assert_restyle_hints_match() {
         // (RESTYLE_SELF | RESTYLE_DESCENDANTS).
         nsRestyleHint_eRestyle_Subtree => RESTYLE_DESCENDANTS,
         nsRestyleHint_eRestyle_LaterSiblings => RESTYLE_LATER_SIBLINGS,
+        nsRestyleHint_eRestyle_CSSAnimations => RESTYLE_CSS_ANIMATIONS,
         nsRestyleHint_eRestyle_StyleAttribute => RESTYLE_STYLE_ATTRIBUTE,
     }
 }
@@ -89,7 +95,7 @@ impl RestyleHint {
     /// The subset hints that affect the styling of a single element during the
     /// traversal.
     pub fn for_self() -> Self {
-        RESTYLE_SELF | RESTYLE_STYLE_ATTRIBUTE
+        RESTYLE_SELF | RESTYLE_STYLE_ATTRIBUTE | RESTYLE_CSS_ANIMATIONS
     }
 }