Auto merge of #20133 - emilio:kill-xbl, r=xidorn

style: Make Shadow DOM not use XBL anymore.

Bug: 1425759
Reviewed-by: xidorn
MozReview-Commit-ID: Jf2iGvLC5de

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/20133)
<!-- Reviewable:end -->

components/style/gecko/generated/bindings.rs

@@ -2298,6 +2298,19 @@ extern "C" {
         gecko_sheet: *const ServoStyleSheet,
     );
 }
+extern "C" {
+    pub fn Servo_AuthorStyles_RemoveStyleSheet(
+        self_: RawServoAuthorStylesBorrowedMut,
+        gecko_sheet: *const ServoStyleSheet,
+    );
+}
+extern "C" {
+    pub fn Servo_AuthorStyles_InsertStyleSheetBefore(
+        self_: RawServoAuthorStylesBorrowedMut,
+        gecko_sheet: *const ServoStyleSheet,
+        before: *const ServoStyleSheet,
+    );
+}
 extern "C" {
     pub fn Servo_AuthorStyles_ForceDirty(self_: RawServoAuthorStylesBorrowedMut);
 }

components/style/gecko/wrapper.rs

@@ -959,7 +959,8 @@ impl<'le> TElement for GeckoElement<'le> {
         // ::before/::after, XBL bindings, or nsIAnonymousContentCreators.
         if self.is_in_anonymous_subtree() ||
            self.has_xbl_binding_with_content() ||
-           self.is_in_shadow_tree() ||
+           self.is_html_slot_element() ||
+           self.shadow_root().is_some() ||
            self.may_have_anonymous_children() {
             unsafe {
                 let mut iter: structs::StyleChildrenIterator = ::std::mem::zeroed();
@@ -990,7 +991,7 @@ impl<'le> TElement for GeckoElement<'le> {
             return self.as_node().owner_doc().as_node();
         }
 
-        if self.xbl_binding().is_some() {
+        if self.xbl_binding().is_some() || self.shadow_root().is_some() {
             return self.as_node();
         }
 
@@ -1408,19 +1409,36 @@ impl<'le> TElement for GeckoElement<'le> {
         // If we are a NAC pseudo-element, we want to get rules from our
         // rule_hash_target, that is, our originating element.
         let mut current = Some(self.rule_hash_target());
-
         while let Some(element) = current {
+            // TODO(emilio): Deal with Shadow DOM separately than with XBL
+            // (right now we still rely on get_xbl_binding_parent()).
+            //
+            // That will allow to clean up a bunch in
+            // push_applicable_declarations.
+            if let Some(shadow) = element.shadow_root() {
+                debug_assert!(!shadow.mServoStyles.mPtr.is_null());
+                let author_styles = unsafe {
+                    &*(shadow.mServoStyles.mPtr
+                        as *const structs::RawServoAuthorStyles
+                        as *const bindings::RawServoAuthorStyles)
+                };
+
+                let author_styles: &'a _ = AuthorStyles::<GeckoStyleSheet>::from_ffi(author_styles);
+                f(&author_styles.data, author_styles.quirks_mode);
+                if element != *self {
+                    break;
+                }
+            }
+
             if let Some(binding) = element.xbl_binding() {
                 binding.each_xbl_cascade_data(&mut f);
 
                 // If we're not looking at our original element, allow the
                 // binding to cut off style inheritance.
-                if element != *self {
-                    if !binding.inherits_style() {
-                        // Go no further; we're not inheriting style from
-                        // anything above here.
-                        break;
-                    }
+                if element != *self && !binding.inherits_style() {
+                    // Go no further; we're not inheriting style from
+                    // anything above here.
+                    break;
                 }
             }
 

ports/geckolib/glue.rs

@@ -1149,6 +1149,40 @@ pub unsafe extern "C" fn Servo_AuthorStyles_AppendStyleSheet(
     styles.stylesheets.append_stylesheet(None, sheet, &guard);
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn Servo_AuthorStyles_InsertStyleSheetBefore(
+    styles: RawServoAuthorStylesBorrowedMut,
+    sheet: *const ServoStyleSheet,
+    before_sheet: *const ServoStyleSheet,
+) {
+    let styles = AuthorStyles::<GeckoStyleSheet>::from_ffi_mut(styles);
+
+    let global_style_data = &*GLOBAL_STYLE_DATA;
+    let guard = global_style_data.shared_lock.read();
+    styles.stylesheets.insert_stylesheet_before(
+        None,
+        GeckoStyleSheet::new(sheet),
+        GeckoStyleSheet::new(before_sheet),
+        &guard,
+    );
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn Servo_AuthorStyles_RemoveStyleSheet(
+    styles: RawServoAuthorStylesBorrowedMut,
+    sheet: *const ServoStyleSheet,
+) {
+    let styles = AuthorStyles::<GeckoStyleSheet>::from_ffi_mut(styles);
+
+    let global_style_data = &*GLOBAL_STYLE_DATA;
+    let guard = global_style_data.shared_lock.read();
+    styles.stylesheets.remove_stylesheet(
+        None,
+        GeckoStyleSheet::new(sheet),
+        &guard,
+    );
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn Servo_AuthorStyles_ForceDirty(
     styles: RawServoAuthorStylesBorrowedMut,