servo: Merge #18823 - Support pseudo-element properly in HasAuthorSpecifiedRules (from upsuper:author-pseudo); r=emilio

This is the Servo side change of [bug 1401825](https://bugzilla.mozilla.org/show_bug.cgi?id=1401825).

Source-Repo: https://github.com/servo/servo
Source-Revision: 3c6e7b56c3469d29df8f6ff3332f50e447671d91

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 4b570a20513ce9bef7e4a4c653293376647ee740

servo/components/style/gecko/generated/bindings.rs

@@ -2944,7 +2944,9 @@ extern "C" {
                                   primary_style: ServoStyleContextBorrowed);
 }
 extern "C" {
-    pub fn Servo_HasAuthorSpecifiedRules(element: RawGeckoElementBorrowed,
+    pub fn Servo_HasAuthorSpecifiedRules(style: ServoStyleContextBorrowed,
+                                         element: RawGeckoElementBorrowed,
+                                         pseudo_type: CSSPseudoElementType,
                                          rule_type_mask: u32,
                                          author_colors_allowed: bool) -> bool;
 }

servo/components/style/rule_tree/mod.rs

@@ -7,6 +7,8 @@
 //! The rule tree.
 
 use applicable_declarations::ApplicableDeclarationList;
+#[cfg(feature = "gecko")]
+use gecko::selector_parser::PseudoElement;
 #[cfg(feature = "servo")]
 use heapsize::HeapSizeOf;
 #[cfg(feature = "gecko")]
@@ -1077,6 +1079,7 @@ impl StrongRuleNode {
     #[cfg(feature = "gecko")]
     pub fn has_author_specified_rules<E>(&self,
                                          mut element: E,
+                                         mut pseudo: Option<PseudoElement>,
                                          guards: &StylesheetGuards,
                                          rule_type_mask: u32,
                                          author_colors_allowed: bool)
@@ -1291,14 +1294,20 @@ impl StrongRuleNode {
             if !have_explicit_ua_inherit { break }
 
             // Continue to the parent element and search for the inherited properties.
-            element = match element.inheritance_parent() {
-                Some(parent) => parent,
-                None => break
-            };
+            if let Some(pseudo) = pseudo.take() {
+                if pseudo.inherits_from_default_values() {
+                    break;
+                }
+            } else {
+                element = match element.inheritance_parent() {
+                    Some(parent) => parent,
+                    None => break
+                };
 
-            let parent_data = element.mutate_data().unwrap();
-            let parent_rule_node = parent_data.styles.primary().rules().clone();
-            element_rule_node = Cow::Owned(parent_rule_node);
+                let parent_data = element.mutate_data().unwrap();
+                let parent_rule_node = parent_data.styles.primary().rules().clone();
+                element_rule_node = Cow::Owned(parent_rule_node);
+            }
 
             properties = inherited_properties;
         }

servo/ports/geckolib/glue.rs

@@ -1863,26 +1863,24 @@ pub extern "C" fn Servo_SetExplicitStyle(element: RawGeckoElementBorrowed,
 }
 
 #[no_mangle]
-pub extern "C" fn Servo_HasAuthorSpecifiedRules(element: RawGeckoElementBorrowed,
+pub extern "C" fn Servo_HasAuthorSpecifiedRules(style: ServoStyleContextBorrowed,
+                                                element: RawGeckoElementBorrowed,
+                                                pseudo_type: CSSPseudoElementType,
                                                 rule_type_mask: u32,
                                                 author_colors_allowed: bool)
     -> bool
 {
     let element = GeckoElement(element);
-
-    let data =
-        element.borrow_data()
-        .expect("calling Servo_HasAuthorSpecifiedRules on an unstyled element");
-
-    let primary_style = data.styles.primary();
+    let pseudo = PseudoElement::from_pseudo_type(pseudo_type);
 
     let guard = (*GLOBAL_STYLE_DATA).shared_lock.read();
     let guards = StylesheetGuards::same(&guard);
 
-    primary_style.rules().has_author_specified_rules(element,
-                                                     &guards,
-                                                     rule_type_mask,
-                                                     author_colors_allowed)
+    style.rules().has_author_specified_rules(element,
+                                             pseudo,
+                                             &guards,
+                                             rule_type_mask,
+                                             author_colors_allowed)
 }
 
 fn get_pseudo_style(