Make StyleSheetListOwner an enum instead of a trait object

components/script/dom/document.rs

@@ -3191,6 +3191,65 @@ impl Document {
         }
         self.shadow_roots_styles_changed.set(false);
     }
+
+    pub fn stylesheet_count(&self) -> usize {
+        self.stylesheets.borrow().len()
+    }
+
+    pub fn stylesheet_at(&self, index: usize) -> Option<DomRoot<CSSStyleSheet>> {
+        let stylesheets = self.stylesheets.borrow();
+
+        stylesheets
+            .get(Origin::Author, index)
+            .and_then(|s| s.owner.upcast::<Node>().get_cssom_stylesheet())
+    }
+
+    /// Add a stylesheet owned by `owner` to the list of document sheets, in the
+    /// correct tree position.
+    #[allow(unrooted_must_root)] // Owner needs to be rooted already necessarily.
+    pub fn add_stylesheet(&self, owner: &Element, sheet: Arc<Stylesheet>) {
+        let stylesheets = &mut *self.stylesheets.borrow_mut();
+        let insertion_point = stylesheets
+            .iter()
+            .map(|(sheet, _origin)| sheet)
+            .find(|sheet_in_doc| {
+                owner
+                    .upcast::<Node>()
+                    .is_before(sheet_in_doc.owner.upcast())
+            })
+            .cloned();
+
+        self.window
+            .layout_chan()
+            .send(Msg::AddStylesheet(
+                sheet.clone(),
+                insertion_point.as_ref().map(|s| s.sheet.clone()),
+            ))
+            .unwrap();
+
+        DocumentOrShadowRoot::add_stylesheet(
+            owner,
+            StylesheetSet::Document(stylesheets),
+            sheet,
+            insertion_point,
+            self.style_shared_lock(),
+        );
+    }
+
+    /// Remove a stylesheet owned by `owner` from the list of document sheets.
+    #[allow(unrooted_must_root)] // Owner needs to be rooted already necessarily.
+    pub fn remove_stylesheet(&self, owner: &Element, s: &Arc<Stylesheet>) {
+        self.window
+            .layout_chan()
+            .send(Msg::RemoveStylesheet(s.clone()))
+            .unwrap();
+
+        DocumentOrShadowRoot::remove_stylesheet(
+            owner,
+            s,
+            StylesheetSet::Document(&mut *self.stylesheets.borrow_mut()),
+        )
+    }
 }
 
 impl Element {
@@ -3222,8 +3281,12 @@ impl ProfilerMetadataFactory for Document {
 impl DocumentMethods for Document {
     // https://drafts.csswg.org/cssom/#dom-document-stylesheets
     fn StyleSheets(&self) -> DomRoot<StyleSheetList> {
-        self.stylesheet_list
+        self.stylesheet_list.or_init(|| {
-            .or_init(|| StyleSheetList::new(&self.window, Box::new(Dom::from_ref(self))))
+            StyleSheetList::new(
+                &self.window,
+                StyleSheetListOwner::Document(Dom::from_ref(self)),
+            )
+        })
     }
 
     // https://dom.spec.whatwg.org/#dom-document-implementation
@@ -4606,68 +4669,3 @@ impl PendingScript {
             .map(|result| (DomRoot::from_ref(&*self.element), result))
     }
 }
-
-impl StyleSheetListOwner for Dom<Document> {
-    fn stylesheet_count(&self) -> usize {
-        self.stylesheets.borrow().len()
-    }
-
-    fn stylesheet_at(&self, index: usize) -> Option<DomRoot<CSSStyleSheet>> {
-        let stylesheets = self.stylesheets.borrow();
-
-        stylesheets
-            .get(Origin::Author, index)
-            .and_then(|s| s.owner.upcast::<Node>().get_cssom_stylesheet())
-    }
-
-    /// Add a stylesheet owned by `owner` to the list of document sheets, in the
-    /// correct tree position.
-    #[allow(unrooted_must_root)] // Owner needs to be rooted already necessarily.
-    fn add_stylesheet(&self, owner: &Element, sheet: Arc<Stylesheet>) {
-        let stylesheets = &mut *self.stylesheets.borrow_mut();
-        let insertion_point = stylesheets
-            .iter()
-            .map(|(sheet, _origin)| sheet)
-            .find(|sheet_in_doc| {
-                owner
-                    .upcast::<Node>()
-                    .is_before(sheet_in_doc.owner.upcast())
-            })
-            .cloned();
-
-        self.window
-            .layout_chan()
-            .send(Msg::AddStylesheet(
-                sheet.clone(),
-                insertion_point.as_ref().map(|s| s.sheet.clone()),
-            ))
-            .unwrap();
-
-        DocumentOrShadowRoot::add_stylesheet(
-            owner,
-            StylesheetSet::Document(stylesheets),
-            sheet,
-            insertion_point,
-            self.style_shared_lock(),
-        );
-    }
-
-    /// Remove a stylesheet owned by `owner` from the list of document sheets.
-    #[allow(unrooted_must_root)] // Owner needs to be rooted already necessarily.
-    fn remove_stylesheet(&self, owner: &Element, s: &Arc<Stylesheet>) {
-        self.window
-            .layout_chan()
-            .send(Msg::RemoveStylesheet(s.clone()))
-            .unwrap();
-
-        DocumentOrShadowRoot::remove_stylesheet(
-            owner,
-            s,
-            StylesheetSet::Document(&mut *self.stylesheets.borrow_mut()),
-        )
-    }
-
-    fn invalidate_stylesheets(&self) {
-        Document::invalidate_stylesheets(self);
-    }
-}

components/script/dom/htmllinkelement.rs

@@ -109,6 +109,7 @@ impl HTMLLinkElement {
 
     // FIXME(emilio): These methods are duplicated with
     // HTMLStyleElement::set_stylesheet.
+    #[allow(unrooted_must_root)]
     pub fn set_stylesheet(&self, s: Arc<Stylesheet>) {
         let stylesheets_owner = stylesheets_owner_from_node(self);
         if let Some(ref s) = *self.stylesheet.borrow() {

components/script/dom/htmlmetaelement.rs

@@ -99,6 +99,7 @@ impl HTMLMetaElement {
         }
     }
 
+    #[allow(unrooted_must_root)]
     fn apply_viewport(&self) {
         if !pref!(layout.viewport.enabled) {
             return;

components/script/dom/htmlstyleelement.rs

@@ -138,6 +138,7 @@ impl HTMLStyleElement {
     }
 
     // FIXME(emilio): This is duplicated with HTMLLinkElement::set_stylesheet.
+    #[allow(unrooted_must_root)]
     pub fn set_stylesheet(&self, s: Arc<Stylesheet>) {
         let stylesheets_owner = stylesheets_owner_from_node(self);
         if let Some(ref s) = *self.stylesheet.borrow() {

components/script/dom/node.rs

@@ -2802,13 +2802,14 @@ pub fn shadow_root_from_node<T: DerivedFrom<Node> + DomObject>(
     derived.upcast().owner_shadow_root()
 }
 
+#[allow(unrooted_must_root)]
 pub fn stylesheets_owner_from_node<T: DerivedFrom<Node> + DomObject>(
     derived: &T,
-) -> Box<StyleSheetListOwner> {
+) -> StyleSheetListOwner {
     if let Some(shadow_root) = shadow_root_from_node(derived) {
-        Box::new(Dom::from_ref(&*shadow_root))
+        StyleSheetListOwner::ShadowRoot(Dom::from_ref(&*shadow_root))
     } else {
-        Box::new(Dom::from_ref(&*document_from_node(derived)))
+        StyleSheetListOwner::Document(Dom::from_ref(&*document_from_node(derived)))
     }
 }
 

components/script/dom/shadowroot.rs

@@ -75,6 +75,50 @@ impl ShadowRoot {
         None
     }
 
+    pub fn stylesheet_count(&self) -> usize {
+        self.author_styles.borrow().stylesheets.len()
+    }
+
+    pub fn stylesheet_at(&self, index: usize) -> Option<DomRoot<CSSStyleSheet>> {
+        let stylesheets = &self.author_styles.borrow().stylesheets;
+
+        stylesheets
+            .get(index)
+            .and_then(|s| s.owner.upcast::<Node>().get_cssom_stylesheet())
+    }
+
+    /// Add a stylesheet owned by `owner` to the list of shadow root sheets, in the
+    /// correct tree position.
+    #[allow(unrooted_must_root)] // Owner needs to be rooted already necessarily.
+    pub fn add_stylesheet(&self, owner: &Element, sheet: Arc<Stylesheet>) {
+        let stylesheets = &mut self.author_styles.borrow_mut().stylesheets;
+        let insertion_point = stylesheets
+            .iter()
+            .find(|sheet_in_shadow| {
+                owner
+                    .upcast::<Node>()
+                    .is_before(sheet_in_shadow.owner.upcast())
+            })
+            .cloned();
+        DocumentOrShadowRoot::add_stylesheet(
+            owner,
+            StylesheetSet::Author(stylesheets),
+            sheet,
+            insertion_point,
+            self.document.style_shared_lock(),
+        );
+    }
+
+    /// Remove a stylesheet owned by `owner` from the list of shadow root sheets.
+    #[allow(unrooted_must_root)] // Owner needs to be rooted already necessarily.
+    pub fn remove_stylesheet(&self, owner: &Element, s: &Arc<Stylesheet>) {
+        DocumentOrShadowRoot::remove_stylesheet(
+            owner,
+            s,
+            StylesheetSet::Author(&mut self.author_styles.borrow_mut().stylesheets),
+        )
+    }
+
     pub fn invalidate_stylesheets(&self) {
         self.document.invalidate_shadow_roots_stylesheets();
         self.author_styles.borrow_mut().stylesheets.force_dirty();
@@ -145,8 +189,12 @@ impl ShadowRootMethods for ShadowRoot {
 
     // https://drafts.csswg.org/cssom/#dom-document-stylesheets
     fn StyleSheets(&self) -> DomRoot<StyleSheetList> {
-        self.stylesheet_list
+        self.stylesheet_list.or_init(|| {
-            .or_init(|| StyleSheetList::new(&self.window, Box::new(Dom::from_ref(self))))
+            StyleSheetList::new(
+                &self.window,
+                StyleSheetListOwner::ShadowRoot(Dom::from_ref(self)),
+            )
+        })
     }
 }
 
@@ -193,53 +241,3 @@ impl LayoutShadowRootHelpers for LayoutDom<ShadowRoot> {
         }
     }
 }
-
-impl StyleSheetListOwner for Dom<ShadowRoot> {
-    fn stylesheet_count(&self) -> usize {
-        self.author_styles.borrow().stylesheets.len()
-    }
-
-    fn stylesheet_at(&self, index: usize) -> Option<DomRoot<CSSStyleSheet>> {
-        let stylesheets = &self.author_styles.borrow().stylesheets;
-
-        stylesheets
-            .get(index)
-            .and_then(|s| s.owner.upcast::<Node>().get_cssom_stylesheet())
-    }
-
-    /// Add a stylesheet owned by `owner` to the list of shadow root sheets, in the
-    /// correct tree position.
-    #[allow(unrooted_must_root)] // Owner needs to be rooted already necessarily.
-    fn add_stylesheet(&self, owner: &Element, sheet: Arc<Stylesheet>) {
-        let stylesheets = &mut self.author_styles.borrow_mut().stylesheets;
-        let insertion_point = stylesheets
-            .iter()
-            .find(|sheet_in_shadow| {
-                owner
-                    .upcast::<Node>()
-                    .is_before(sheet_in_shadow.owner.upcast())
-            })
-            .cloned();
-        DocumentOrShadowRoot::add_stylesheet(
-            owner,
-            StylesheetSet::Author(stylesheets),
-            sheet,
-            insertion_point,
-            self.document.style_shared_lock(),
-        );
-    }
-
-    /// Remove a stylesheet owned by `owner` from the list of shadow root sheets.
-    #[allow(unrooted_must_root)] // Owner needs to be rooted already necessarily.
-    fn remove_stylesheet(&self, owner: &Element, s: &Arc<Stylesheet>) {
-        DocumentOrShadowRoot::remove_stylesheet(
-            owner,
-            s,
-            StylesheetSet::Author(&mut self.author_styles.borrow_mut().stylesheets),
-        )
-    }
-
-    fn invalidate_stylesheets(&self) {
-        ShadowRoot::invalidate_stylesheets(self);
-    }
-}

components/script/dom/stylesheetlist.rs

@@ -5,33 +5,76 @@
 use crate::dom::bindings::codegen::Bindings::StyleSheetListBinding;
 use crate::dom::bindings::codegen::Bindings::StyleSheetListBinding::StyleSheetListMethods;
 use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
-use crate::dom::bindings::root::DomRoot;
+use crate::dom::bindings::root::{Dom, DomRoot};
-use crate::dom::bindings::trace::JSTraceable;
 use crate::dom::cssstylesheet::CSSStyleSheet;
+use crate::dom::document::Document;
 use crate::dom::element::Element;
+use crate::dom::shadowroot::ShadowRoot;
 use crate::dom::stylesheet::StyleSheet;
 use crate::dom::window::Window;
 use dom_struct::dom_struct;
 use servo_arc::Arc;
 use style::stylesheets::Stylesheet;
 
-pub trait StyleSheetListOwner: JSTraceable {
+#[must_root]
-    fn stylesheet_count(&self) -> usize;
+#[derive(JSTraceable, MallocSizeOf)]
-    fn stylesheet_at(&self, index: usize) -> Option<DomRoot<CSSStyleSheet>>;
+pub enum StyleSheetListOwner {
-    fn add_stylesheet(&self, owner: &Element, sheet: Arc<Stylesheet>);
+    Document(Dom<Document>),
-    fn remove_stylesheet(&self, owner: &Element, s: &Arc<Stylesheet>);
+    ShadowRoot(Dom<ShadowRoot>),
-    fn invalidate_stylesheets(&self);
+}
+
+impl StyleSheetListOwner {
+    pub fn stylesheet_count(&self) -> usize {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.stylesheet_count(),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => shadow_root.stylesheet_count(),
+        }
+    }
+
+    pub fn stylesheet_at(&self, index: usize) -> Option<DomRoot<CSSStyleSheet>> {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.stylesheet_at(index),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => shadow_root.stylesheet_at(index),
+        }
+    }
+
+    pub fn add_stylesheet(&self, owner: &Element, sheet: Arc<Stylesheet>) {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.add_stylesheet(owner, sheet),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => {
+                shadow_root.add_stylesheet(owner, sheet)
+            },
+        }
+    }
+
+    pub fn remove_stylesheet(&self, owner: &Element, s: &Arc<Stylesheet>) {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.remove_stylesheet(owner, s),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => {
+                shadow_root.remove_stylesheet(owner, s)
+            },
+        }
+    }
+
+    pub fn invalidate_stylesheets(&self) {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.invalidate_stylesheets(),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => {
+                shadow_root.invalidate_stylesheets()
+            },
+        }
+    }
 }
 
 #[dom_struct]
 pub struct StyleSheetList {
     reflector_: Reflector,
-    #[ignore_malloc_size_of = "trait object"]
+    document_or_shadow_root: StyleSheetListOwner,
-    document_or_shadow_root: Box<StyleSheetListOwner>,
 }
 
 impl StyleSheetList {
-    fn new_inherited(doc_or_sr: Box<StyleSheetListOwner>) -> StyleSheetList {
+    #[allow(unrooted_must_root)]
+    fn new_inherited(doc_or_sr: StyleSheetListOwner) -> StyleSheetList {
         StyleSheetList {
             reflector_: Reflector::new(),
             document_or_shadow_root: doc_or_sr,
@@ -39,7 +82,7 @@ impl StyleSheetList {
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, doc_or_sr: Box<StyleSheetListOwner>) -> DomRoot<StyleSheetList> {
+    pub fn new(window: &Window, doc_or_sr: StyleSheetListOwner) -> DomRoot<StyleSheetList> {
         reflect_dom_object(
             Box::new(StyleSheetList::new_inherited(doc_or_sr)),
             window,