Arc all Vec<CSSRule>s, put in CSSRules type

components/script/dom/htmlmetaelement.rs

@@ -81,7 +81,7 @@ impl HTMLMetaElement {
             if !content.is_empty() {
                 if let Some(translated_rule) = ViewportRule::from_meta(&**content) {
                     *self.stylesheet.borrow_mut() = Some(Arc::new(Stylesheet {
-                        rules: vec![CssRule::Viewport(Arc::new(RwLock::new(translated_rule)))],
+                        rules: vec![CssRule::Viewport(Arc::new(RwLock::new(translated_rule)))].into(),
                         origin: Origin::Author,
                         media: Default::default(),
                         // Viewport constraints are always recomputed on resize; they don't need to

components/style/selector_matching.rs

@@ -380,15 +380,15 @@ impl Stylist {
                             return true
                         }
                     }
-                    mq_eval_changed(rules, before, after)
+                    mq_eval_changed(&rules, before, after)
                 }) {
                     return true
                 }
             }
             false
         }
         self.is_device_dirty |= stylesheets.iter().any(|stylesheet| {
-            mq_eval_changed(&stylesheet.rules, &self.device, &device)
+            mq_eval_changed(&stylesheet.rules.0, &self.device, &device)
         });
 
         self.device = device;

components/style/stylesheets.rs

@@ -39,12 +39,20 @@ pub enum Origin {
     User,
 }
 
+#[derive(Debug)]
+pub struct CssRules(pub Arc<Vec<CssRule>>);
+
+impl From<Vec<CssRule>> for CssRules {
+    fn from(other: Vec<CssRule>) -> Self {
+        CssRules(Arc::new(other))
+    }
+}
 
 #[derive(Debug)]
 pub struct Stylesheet {
     /// List of rules in the order they were found (important for
     /// cascading order)
-    pub rules: Vec<CssRule>,
+    pub rules: CssRules,
     /// List of media associated with the Stylesheet.
     pub media: MediaList,
     pub origin: Origin,
@@ -89,7 +97,7 @@ impl CssRule {
             CssRule::Media(ref lock) => {
                 let media_rule = lock.read();
                 let mq = media_rule.media_queries.read();
-                f(&media_rule.rules, Some(&mq))
+                f(&media_rule.rules.0, Some(&mq))
             }
         }
     }
@@ -112,7 +120,7 @@ pub struct KeyframesRule {
 #[derive(Debug)]
 pub struct MediaRule {
     pub media_queries: Arc<RwLock<MediaList>>,
-    pub rules: Vec<CssRule>,
+    pub rules: CssRules,
 }
 
 #[derive(Debug)]
@@ -180,7 +188,7 @@ impl Stylesheet {
 
         Stylesheet {
             origin: origin,
-            rules: rules,
+            rules: rules.into(),
             media: Default::default(),
             dirty_on_viewport_size_change:
                 input.seen_viewport_percentages(),
@@ -208,7 +216,7 @@ impl Stylesheet {
     /// examined.
     #[inline]
     pub fn effective_rules<F>(&self, device: &Device, mut f: F) where F: FnMut(&CssRule) {
-        effective_rules(&self.rules, device, &mut f);
+        effective_rules(&self.rules.0, device, &mut f);
     }
 }
 
@@ -251,7 +259,7 @@ rule_filter! {
     effective_keyframes_rules(Keyframes => KeyframesRule),
 }
 
-fn parse_nested_rules(context: &ParserContext, input: &mut Parser) -> Vec<CssRule> {
+fn parse_nested_rules(context: &ParserContext, input: &mut Parser) -> CssRules {
     let mut iter = RuleListParser::new_for_nested_rule(input,
                                                        NestedRuleParser { context: context });
     let mut rules = Vec::new();
@@ -265,7 +273,7 @@ fn parse_nested_rules(context: &ParserContext, input: &mut Parser) -> Vec<CssRul
             }
         }
     }
-    rules
+    rules.into()
 }