First bits of shadow dom layout

components/script/dom/element.rs

@@ -15,6 +15,7 @@ use crate::dom::bindings::codegen::Bindings::EventBinding::EventMethods;
 use crate::dom::bindings::codegen::Bindings::FunctionBinding::Function;
 use crate::dom::bindings::codegen::Bindings::HTMLTemplateElementBinding::HTMLTemplateElementMethods;
 use crate::dom::bindings::codegen::Bindings::NodeBinding::{GetRootNodeOptions, NodeMethods};
+use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::ShadowRootBinding::ShadowRootMethods;
 use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use crate::dom::bindings::codegen::Bindings::WindowBinding::{ScrollBehavior, ScrollToOptions};
 use crate::dom::bindings::codegen::UnionTypes::NodeOrString;
@@ -76,7 +77,7 @@ use crate::dom::node::{NodeDamage, NodeFlags, UnbindContext};
 use crate::dom::nodelist::NodeList;
 use crate::dom::promise::Promise;
 use crate::dom::servoparser::ServoParser;
-use crate::dom::shadowroot::ShadowRoot;
+use crate::dom::shadowroot::{LayoutShadowRootHelpers, ShadowRoot};
 use crate::dom::text::Text;
 use crate::dom::validation::Validatable;
 use crate::dom::virtualmethods::{vtable_for, VirtualMethods};
@@ -587,6 +588,9 @@ pub trait LayoutElementHelpers {
     fn get_state_for_layout(&self) -> ElementState;
     fn insert_selector_flags(&self, flags: ElementSelectorFlags);
     fn has_selector_flags(&self, flags: ElementSelectorFlags) -> bool;
+    /// The shadow root this element is a host of.
+    #[allow(unsafe_code)]
+    unsafe fn get_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>>;
 }
 
 impl LayoutElementHelpers for LayoutDom<Element> {
@@ -1049,6 +1053,12 @@ impl LayoutElementHelpers for LayoutDom<Element> {
     fn has_selector_flags(&self, flags: ElementSelectorFlags) -> bool {
         unsafe { (*self.unsafe_get()).selector_flags.get().contains(flags) }
     }
+
+    #[inline]
+    #[allow(unsafe_code)]
+    unsafe fn get_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>> {
+        (*self.unsafe_get()).shadow_root.get_inner_as_layout()
+    }
 }
 
 impl Element {
@@ -2877,11 +2887,18 @@ impl<'a> SelectorsElement for DomRoot<Element> {
     }
 
     fn parent_node_is_shadow_root(&self) -> bool {
-        false
+        match self.upcast::<Node>().GetParentNode() {
+            None => false,
+            Some(node) => node.is::<ShadowRoot>(),
+        }
     }
 
     fn containing_shadow_host(&self) -> Option<Self> {
-        None
+        if let Some(shadow_root) = self.upcast::<Node>().owner_shadow_root() {
+            Some(shadow_root.Host())
+        } else {
+            None
+        }
     }
 
     fn match_pseudo_element(

components/script/dom/node.rs

@@ -295,8 +295,8 @@ impl Node {
             if parent_in_shadow_tree {
                 if let Some(shadow_root) = self.downcast::<ShadowRoot>() {
                     node.set_owner_shadow_root(&*shadow_root);
-                } else {
-                    node.set_owner_shadow_root(&*self.owner_shadow_root());
+                } else if let Some(shadow_root) = self.owner_shadow_root() {
+                    node.set_owner_shadow_root(&*shadow_root);
                 }
             }
             let mut is_connected = parent_is_connected;
@@ -946,8 +946,8 @@ impl Node {
         self.owner_doc.set(Some(document));
     }
 
-    pub fn owner_shadow_root(&self) -> DomRoot<ShadowRoot> {
-        self.owner_shadow_root.get().unwrap()
+    pub fn owner_shadow_root(&self) -> Option<DomRoot<ShadowRoot>> {
+        self.owner_shadow_root.get()
     }
 
     pub fn set_owner_shadow_root(&self, shadow_root: &ShadowRoot) {
@@ -1184,6 +1184,7 @@ pub trait LayoutNodeHelpers {
     unsafe fn next_sibling_ref(&self) -> Option<LayoutDom<Node>>;
 
     unsafe fn owner_doc_for_layout(&self) -> LayoutDom<Document>;
+    unsafe fn owner_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>>;
 
     unsafe fn is_element_for_layout(&self) -> bool;
     unsafe fn get_flag(&self, flag: NodeFlags) -> bool;
@@ -1260,6 +1261,12 @@ impl LayoutNodeHelpers for LayoutDom<Node> {
             .unwrap()
     }
 
+    #[inline]
+    #[allow(unsafe_code)]
+    unsafe fn owner_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>> {
+        (*self.unsafe_get()).owner_shadow_root.get_inner_as_layout()
+    }
+
     #[inline]
     #[allow(unsafe_code)]
     unsafe fn get_flag(&self, flag: NodeFlags) -> bool {

components/script/dom/shadowroot.rs

@@ -7,7 +7,7 @@ use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::{self, ShadowRoo
 use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::num::Finite;
 use crate::dom::bindings::reflector::reflect_dom_object;
-use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
+use crate::dom::bindings::root::{Dom, DomRoot, LayoutDom, MutNullableDom};
 use crate::dom::cssstylesheet::CSSStyleSheet;
 use crate::dom::document::Document;
 use crate::dom::documentfragment::DocumentFragment;
@@ -121,3 +121,16 @@ impl ShadowRootMethods for ShadowRoot {
         })
     }
 }
+
+#[allow(unsafe_code)]
+pub trait LayoutShadowRootHelpers {
+    unsafe fn get_host_for_layout(&self) -> LayoutDom<Element>;
+}
+
+impl LayoutShadowRootHelpers for LayoutDom<ShadowRoot> {
+    #[inline]
+    #[allow(unsafe_code)]
+    unsafe fn get_host_for_layout(&self) -> LayoutDom<Element> {
+        (*self.unsafe_get()).host.to_layout()
+    }
+}