style: Optimize @keyframes rule insertions.

Bug: 1435214
Reviewed-by: xidorn,hiro
MozReview-Commit-ID: AHwhZynLBv

components/style/gecko/media_queries.rs

@@ -28,7 +28,7 @@ use style_traits::{CSSPixel, CssWriter, DevicePixel};
 use style_traits::{ToCss, ParseError, StyleParseErrorKind};
 use style_traits::viewport::ViewportConstraints;
 use stylesheets::Origin;
-use values::{CSSFloat, CustomIdent};
+use values::{CSSFloat, CustomIdent, KeyframesName};
 use values::computed::{self, ToComputedValue};
 use values::computed::font::FontSize;
 use values::specified::{Integer, Length, Number};
@@ -71,7 +71,7 @@ impl Device {
     pub fn new(pres_context: RawGeckoPresContextOwned) -> Self {
         assert!(!pres_context.is_null());
         Device {
-            pres_context: pres_context,
+            pres_context,
             default_values: ComputedValues::default_values(unsafe { &*pres_context }),
             // FIXME(bz): Seems dubious?
             root_font_size: AtomicIsize::new(FontSize::medium().size().0 as isize),
@@ -85,11 +85,22 @@ impl Device {
     /// relevant viewport constraints.
     pub fn account_for_viewport_rule(
         &mut self,
-        _constraints: &ViewportConstraints
+        _constraints: &ViewportConstraints,
     ) {
         unreachable!("Gecko doesn't support @viewport");
     }
 
+    /// Whether any animation name may be referenced from the style of any
+    /// element.
+    pub fn animation_name_may_be_referenced(&self, name: &KeyframesName) -> bool {
+        unsafe {
+            bindings::Gecko_AnimationNameMayBeReferencedFromStyle(
+                self.pres_context(),
+                name.as_atom().as_ptr(),
+            )
+        }
+    }
+
     /// Returns the default computed values as a reference, in order to match
     /// Servo.
     pub fn default_computed_values(&self) -> &ComputedValues {

components/style/invalidation/stylesheets.rs

@@ -151,7 +151,7 @@ impl StylesheetInvalidationSet {
         }
 
         for rule in stylesheet.effective_rules(device, guard) {
-            self.collect_invalidations_for_rule(rule, guard);
+            self.collect_invalidations_for_rule(rule, guard, device);
             if self.fully_invalid {
                 self.invalid_scopes.clear();
                 self.invalid_elements.clear();
@@ -393,8 +393,9 @@ impl StylesheetInvalidationSet {
     fn collect_invalidations_for_rule(
         &mut self,
         rule: &CssRule,
-        guard: &SharedRwLockReadGuard)
-    {
+        guard: &SharedRwLockReadGuard,
+        device: &Device,
+    ) {
         use stylesheets::CssRule::*;
         debug!("StylesheetInvalidationSet::collect_invalidations_for_rule");
         debug_assert!(!self.fully_invalid, "Not worth to be here!");
@@ -422,7 +423,17 @@ impl StylesheetInvalidationSet {
                 // information. We'll restyle when the font face loads, if
                 // needed.
             }
-            Keyframes(..) |
+            Keyframes(ref lock) => {
+                let keyframes_rule = lock.read_with(guard);
+                if device.animation_name_may_be_referenced(&keyframes_rule.name) {
+                    debug!(" > Found @keyframes rule potentially referenced \
+                           from the page, marking the whole tree invalid.");
+                    self.fully_invalid = true;
+                } else {
+                    // Do nothing, this animation can't affect the style of
+                    // existing elements.
+                }
+            }
             CounterStyle(..) |
             Page(..) |
             Viewport(..) |

components/style/servo/media_queries.rs

@@ -16,9 +16,9 @@ use std::fmt::{self, Write};
 use std::sync::atomic::{AtomicBool, AtomicIsize, Ordering};
 use style_traits::{CSSPixel, CssWriter, DevicePixel, ToCss, ParseError};
 use style_traits::viewport::ViewportConstraints;
+use values::{specified, KeyframesName};
 use values::computed::{self, ToComputedValue};
 use values::computed::font::FontSize;
-use values::specified;
 
 /// A device is a structure that represents the current media a given document
 /// is displayed in.
@@ -96,6 +96,12 @@ impl Device {
         // Servo doesn't implement this quirk (yet)
     }
 
+    /// Whether a given animation name may be referenced from style.
+    pub fn animation_name_may_be_referenced(&self, _: &KeyframesName) -> bool {
+        // Assume it is, since we don't have any good way to prove it's not.
+        true
+    }
+
     /// Returns whether we ever looked up the root font size of the Device.
     pub fn used_root_font_size(&self) -> bool {
         self.used_root_font_size.load(Ordering::Relaxed)