Detach shadow clean up

components/layout_thread/dom_wrapper.rs

@@ -189,7 +189,9 @@ impl<'lr> TShadowRoot for ServoShadowRoot<'lr> {
     }
 
     fn host(&self) -> ServoLayoutElement<'lr> {
-        ServoLayoutElement::from_layout_js(unsafe { self.shadow_root.get_host_for_layout() })
+        ServoLayoutElement::from_layout_js(unsafe {
+            self.shadow_root.get_host_for_layout().unwrap()
+        })
     }
 
     fn style_data<'a>(&self) -> Option<&'a CascadeData>

components/script/dom/element.rs

@@ -491,7 +491,7 @@ impl Element {
         self.ensure_rare_data().shadow_root = Some(Dom::from_ref(&*shadow_root));
         shadow_root
             .upcast::<Node>()
-            .set_containing_shadow_root(&shadow_root);
+            .set_containing_shadow_root(Some(&shadow_root));
 
         if self.is_connected() {
             self.node.owner_doc().register_shadow_root(&*shadow_root);
@@ -504,6 +504,7 @@ impl Element {
 
     pub fn detach_shadow(&self) {
         if let Some(ref shadow_root) = self.shadow_root() {
+            shadow_root.detach();
             self.node.owner_doc().unregister_shadow_root(shadow_root);
             self.ensure_rare_data().shadow_root = None;
         } else {

components/script/dom/htmlmediaelement.rs

@@ -1737,7 +1737,7 @@ impl HTMLMediaElement {
             // if we are already showing the controls.
             return;
         }
-        if let Ok(shadow_root) = element.attach_shadow(IsUserAgentWidget::Yes) {
+        let shadow_root = element.attach_shadow(IsUserAgentWidget::Yes).unwrap();
         let document = document_from_node(self);
         let script = HTMLScriptElement::new(
             local_name!("script"),
@@ -1745,8 +1745,7 @@ impl HTMLMediaElement {
             &document,
             ElementCreator::ScriptCreated,
         );
-            let mut media_controls_script =
+        let mut media_controls_script = resources::read_string(EmbedderResource::MediaControlsJS);
-                resources::read_string(EmbedderResource::MediaControlsJS);
         // This is our hacky way to temporarily workaround the lack of a privileged
         // JS context.
         // The media controls UI accesses the document.servoGetMediaControls(id) API
@@ -1786,7 +1785,6 @@ impl HTMLMediaElement {
 
         self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
     }
-    }
 
     fn remove_controls(&self) {
         if let Some(ref id) = *self.media_controls_id.borrow() {

components/script/dom/node.rs

@@ -283,7 +283,7 @@ impl Node {
         for node in new_child.traverse_preorder(ShadowIncluding::No) {
             if parent_in_shadow_tree {
                 if let Some(shadow_root) = self.containing_shadow_root() {
-                    node.set_containing_shadow_root(&*shadow_root);
+                    node.set_containing_shadow_root(Some(&*shadow_root));
                 }
                 debug_assert!(node.containing_shadow_root().is_some());
             }
@@ -961,8 +961,8 @@ impl Node {
             .map(|sr| DomRoot::from_ref(&**sr))
     }
 
-    pub fn set_containing_shadow_root(&self, shadow_root: &ShadowRoot) {
+    pub fn set_containing_shadow_root(&self, shadow_root: Option<&ShadowRoot>) {
-        self.ensure_rare_data().containing_shadow_root = Some(Dom::from_ref(shadow_root));
+        self.ensure_rare_data().containing_shadow_root = shadow_root.map(|sr| Dom::from_ref(sr));
     }
 
     pub fn is_in_html_doc(&self) -> bool {
@@ -1241,7 +1241,7 @@ impl LayoutNodeHelpers for LayoutDom<Node> {
         let parent = (*self.unsafe_get()).parent_node.get_inner_as_layout();
         if let Some(ref parent) = parent {
             if let Some(shadow_root) = parent.downcast::<ShadowRoot>() {
-                return Some(shadow_root.get_host_for_layout().upcast());
+                return shadow_root.get_host_for_layout().map(|h| h.upcast());
             }
         }
         parent

components/script/dom/shadowroot.rs

@@ -41,7 +41,7 @@ pub struct ShadowRoot {
     document_fragment: DocumentFragment,
     document_or_shadow_root: DocumentOrShadowRoot,
     document: Dom<Document>,
-    host: Dom<Element>,
+    host: MutNullableDom<Element>,
     /// List of author styles associated with nodes in this shadow tree.
     author_styles: DomRefCell<AuthorStyles<StyleSheetInDocument>>,
     stylesheet_list: MutNullableDom<StyleSheetList>,
@@ -62,7 +62,7 @@ impl ShadowRoot {
             document_fragment,
             document_or_shadow_root: DocumentOrShadowRoot::new(document.window()),
             document: Dom::from_ref(document),
-            host: Dom::from_ref(host),
+            host: MutNullableDom::new(Some(host)),
             author_styles: DomRefCell::new(AuthorStyles::new()),
             stylesheet_list: MutNullableDom::new(None),
             window: Dom::from_ref(document.window()),
@@ -77,6 +77,16 @@ impl ShadowRoot {
         )
     }
 
+    pub fn detach(&self) {
+        self.host.set(None);
+        let node = self.upcast::<Node>();
+        node.set_containing_shadow_root(None);
+        node.set_flag(NodeFlags::IS_CONNECTED, false);
+        for child in node.traverse_preorder(ShadowIncluding::No) {
+            child.set_flag(NodeFlags::IS_CONNECTED, false);
+        }
+    }
+
     pub fn get_focused_element(&self) -> Option<DomRoot<Element>> {
         //XXX get retargeted focused element
         None
@@ -130,9 +140,9 @@ impl ShadowRoot {
         self.document.invalidate_shadow_roots_stylesheets();
         self.author_styles.borrow_mut().stylesheets.force_dirty();
         // Mark the host element dirty so a reflow will be performed.
-        self.host
+        if let Some(host) = self.host.get() {
-            .upcast::<Node>()
+            host.upcast::<Node>().dirty(NodeDamage::NodeStyleDamaged);
-            .dirty(NodeDamage::NodeStyleDamaged);
+        }
     }
 
     /// Remove any existing association between the provided id and any elements
@@ -216,7 +226,9 @@ impl ShadowRootMethods for ShadowRoot {
 
     /// https://dom.spec.whatwg.org/#dom-shadowroot-host
     fn Host(&self) -> DomRoot<Element> {
-        DomRoot::from_ref(&self.host)
+        let host = self.host.get();
+        debug_assert!(host.is_some());
+        host.unwrap()
     }
 
     // https://drafts.csswg.org/cssom/#dom-document-stylesheets
@@ -232,7 +244,7 @@ impl ShadowRootMethods for ShadowRoot {
 
 #[allow(unsafe_code)]
 pub trait LayoutShadowRootHelpers {
-    unsafe fn get_host_for_layout(&self) -> LayoutDom<Element>;
+    unsafe fn get_host_for_layout(&self) -> Option<LayoutDom<Element>>;
     unsafe fn get_style_data_for_layout<'a, E: TElement>(
         &self,
     ) -> &'a AuthorStyles<StyleSheetInDocument>;
@@ -247,8 +259,8 @@ pub trait LayoutShadowRootHelpers {
 impl LayoutShadowRootHelpers for LayoutDom<ShadowRoot> {
     #[inline]
     #[allow(unsafe_code)]
-    unsafe fn get_host_for_layout(&self) -> LayoutDom<Element> {
+    unsafe fn get_host_for_layout(&self) -> Option<LayoutDom<Element>> {
-        (*self.unsafe_get()).host.to_layout()
+        (*self.unsafe_get()).host.get_inner_as_layout()
     }
 
     #[inline]