Inform the devtools about shadow roots on a node (#35294)

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

components/script/devtools.rs

@@ -162,23 +162,24 @@ pub(crate) fn handle_get_children(
                 })
                 .collect();
 
-            let children: Vec<_> = parent
-                .children()
-                .enumerate()
-                .filter_map(|(i, child)| {
-                    // Filter whitespace only text nodes that are not inline level
-                    // https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/examine_and_edit_html/index.html#whitespace-only-text-nodes
-                    let prev_inline = i > 0 && inline[i - 1];
-                    let next_inline = i < inline.len() - 1 && inline[i + 1];
+            let mut children = vec![];
+            if let Some(shadow_root) = parent.downcast::<Element>().and_then(Element::shadow_root) {
+                children.push(shadow_root.upcast::<Node>().summarize());
+            }
+            let children_iter = parent.children().enumerate().filter_map(|(i, child)| {
+                // Filter whitespace only text nodes that are not inline level
+                // https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/examine_and_edit_html/index.html#whitespace-only-text-nodes
+                let prev_inline = i > 0 && inline[i - 1];
+                let next_inline = i < inline.len() - 1 && inline[i + 1];
 
-                    let info = child.summarize();
-                    if !is_whitespace(&info) {
-                        return Some(info);
-                    }
+                let info = child.summarize();
+                if !is_whitespace(&info) {
+                    return Some(info);
+                }
 
-                    (prev_inline && next_inline).then_some(info)
-                })
-                .collect();
+                (prev_inline && next_inline).then_some(info)
+            });
+            children.extend(children_iter);
 
             reply.send(Some(children)).unwrap();
         },

components/script/dom/node.rs

@@ -46,6 +46,7 @@ use uuid::Uuid;
 use xml5ever::serialize as xml_serialize;
 
 use super::globalscope::GlobalScope;
+use crate::conversions::Convert;
 use crate::document_loader::DocumentLoader;
 use crate::dom::attr::Attr;
 use crate::dom::bindings::cell::{DomRefCell, Ref, RefMut};
@@ -60,7 +61,9 @@ use crate::dom::bindings::codegen::Bindings::NodeBinding::{
 use crate::dom::bindings::codegen::Bindings::NodeListBinding::NodeListMethods;
 use crate::dom::bindings::codegen::Bindings::ProcessingInstructionBinding::ProcessingInstructionMethods;
 use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::ShadowRoot_Binding::ShadowRootMethods;
-use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::SlotAssignmentMode;
+use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::{
+    ShadowRootMode, SlotAssignmentMode,
+};
 use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use crate::dom::bindings::codegen::InheritTypes::DocumentFragmentTypeId;
 use crate::dom::bindings::codegen::UnionTypes::NodeOrString;
@@ -1180,8 +1183,28 @@ impl Node {
     pub(crate) fn summarize(&self) -> NodeInfo {
         let USVString(base_uri) = self.BaseURI();
         let node_type = self.NodeType();
+
+        let maybe_shadow_root = self.downcast::<ShadowRoot>();
+        let shadow_root_mode = maybe_shadow_root
+            .map(ShadowRoot::Mode)
+            .map(ShadowRootMode::convert);
+        let host = maybe_shadow_root
+            .map(ShadowRoot::Host)
+            .map(|host| host.upcast::<Node>().unique_id());
+        let is_shadow_host = self
+            .downcast::<Element>()
+            .is_some_and(Element::is_shadow_host);
+
+        let num_children = if is_shadow_host {
+            // Shadow roots count as children
+            self.ChildNodes().Length() as usize + 1
+        } else {
+            self.ChildNodes().Length() as usize
+        };
+
         NodeInfo {
             unique_id: self.unique_id(),
+            host,
             base_uri,
             parent: self
                 .GetParentNode()
@@ -1190,8 +1213,10 @@ impl Node {
             is_top_level_document: node_type == NodeConstants::DOCUMENT_NODE,
             node_name: String::from(self.NodeName()),
             node_value: self.GetNodeValue().map(|v| v.into()),
-            num_children: self.ChildNodes().Length() as usize,
+            num_children,
             attrs: self.downcast().map(Element::summarize).unwrap_or(vec![]),
+            is_shadow_host,
+            shadow_root_mode,
         }
     }
 

components/script/dom/shadowroot.rs

@@ -11,6 +11,7 @@ use style::shared_lock::SharedRwLockReadGuard;
 use style::stylesheets::Stylesheet;
 use style::stylist::{CascadeData, Stylist};
 
+use crate::conversions::Convert;
 use crate::dom::bindings::cell::DomRefCell;
 use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::ShadowRoot_Binding::ShadowRootMethods;
 use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::{
@@ -421,3 +422,12 @@ impl<'dom> LayoutShadowRootHelpers<'dom> for LayoutDom<'dom, ShadowRoot> {
         }
     }
 }
+
+impl Convert<devtools_traits::ShadowRootMode> for ShadowRootMode {
+    fn convert(self) -> devtools_traits::ShadowRootMode {
+        match self {
+            ShadowRootMode::Open => devtools_traits::ShadowRootMode::Open,
+            ShadowRootMode::Closed => devtools_traits::ShadowRootMode::Closed,
+        }
+    }
+}