style: Don't use the current element info for cached validation data.

We can take it straight from the validation target.

components/style/context.rs

@@ -21,7 +21,7 @@ use rule_tree::StrongRuleNode;
 use selector_parser::{EAGER_PSEUDO_COUNT, SnapshotMap};
 use selectors::matching::ElementSelectorFlags;
 use shared_lock::StylesheetGuards;
-use sharing::{ValidationData, StyleSharingCandidateCache};
+use sharing::StyleSharingCandidateCache;
 use std::fmt;
 use std::ops::Add;
 #[cfg(feature = "servo")] use std::sync::Mutex;
@@ -269,8 +269,6 @@ pub struct CurrentElementInfo {
     element: OpaqueNode,
     /// Whether the element is being styled for the first time.
     is_initial_style: bool,
-    /// Lazy cache of the different data used for style sharing.
-    pub validation_data: ValidationData,
     /// A Vec of possibly expired animations. Used only by Servo.
     #[allow(dead_code)]
     pub possibly_expired_animations: Vec<PropertyAnimation>,
@@ -575,7 +573,6 @@ impl<E: TElement> ThreadLocalStyleContext<E> {
         self.current_element_info = Some(CurrentElementInfo {
             element: element.as_node().opaque(),
             is_initial_style: !data.has_styles(),
-            validation_data: ValidationData::default(),
             possibly_expired_animations: Vec::new(),
         });
     }

components/style/sharing/mod.rs

@@ -328,7 +328,7 @@ impl<E: TElement> StyleSharingTarget<E> {
 
     /// Attempts to share a style with another node.
     pub fn share_style_if_possible(
-        mut self,
+        &mut self,
         context: &mut StyleContext<E>,
     ) -> StyleSharingResult {
         let cache = &mut context.thread_local.style_sharing_candidate_cache;
@@ -344,17 +344,17 @@ impl<E: TElement> StyleSharingTarget<E> {
         debug_assert_eq!(bloom_filter.current_parent(),
                          self.element.traversal_parent());
 
-        let result =
-            cache.share_style_if_possible(
-                shared_context,
-                selector_flags_map,
-                bloom_filter,
-                &mut self
-            );
+        cache.share_style_if_possible(
+            shared_context,
+            selector_flags_map,
+            bloom_filter,
+            self
+        )
+    }
 
-        context.thread_local.current_element_info.as_mut().unwrap().validation_data =
-            self.validation_data.take();
-        result
+    /// Gets the validation data used to match against this target, if any.
+    pub fn take_validation_data(&mut self) -> ValidationData {
+        self.validation_data.take()
     }
 }
 

components/style/traversal.rs

@@ -777,7 +777,7 @@ where
             // This is only relevant for animations as of right now.
             important_rules_changed = true;
 
-            let target = StyleSharingTarget::new(element);
+            let mut target = StyleSharingTarget::new(element);
             match target.share_style_if_possible(context) {
                 StyleWasShared(index, styles) => {
                     context.thread_local.statistics.styles_shared += 1;
@@ -791,29 +791,13 @@ where
                         StyleResolverForElement::new(element, context, RuleInclusion::All)
                             .resolve_style_with_default_parents();
 
-                    // If we previously tried to match this element against the
-                    // cache, the revalidation match results will already be
-                    // cached. Otherwise we'll have None, and compute them later
-                    // on-demand.
-                    //
-                    // If we do have the results, grab them here to satisfy the
-                    // borrow checker.
-                    let validation_data =
-                        context.thread_local
-                            .current_element_info
-                            .as_mut().unwrap()
-                            .validation_data
-                            .take();
-
-                    let dom_depth =
-                        context.thread_local.bloom_filter.matching_depth();
                     context.thread_local
                         .style_sharing_candidate_cache
                         .insert_if_possible(
                             &element,
                             new_styles.primary(),
-                            validation_data,
-                            dom_depth
+                            target.take_validation_data(),
+                            context.thread_local.bloom_filter.matching_depth(),
                         );
 
                     new_styles