diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 599efd4a8cc..20b51fbfaa1 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -14,7 +14,7 @@ use crate::dom::bindings::codegen::Bindings::ElementBinding::ElementMethods;
 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::NodeMethods;
+use crate::dom::bindings::codegen::Bindings::NodeBinding::{GetRootNodeOptions, NodeMethods};
 use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use crate::dom::bindings::codegen::Bindings::WindowBinding::{ScrollBehavior, ScrollToOptions};
 use crate::dom::bindings::codegen::UnionTypes::NodeOrString;
@@ -484,9 +484,6 @@ impl Element {
             return Err(Error::InvalidState);
         }
 
-        self.upcast::<Node>()
-            .set_flag(NodeFlags::IS_IN_SHADOW_TREE, true);
-
         // Steps 4, 5 and 6.
         Ok(self
             .shadow_root
@@ -3293,7 +3290,9 @@ impl Element {
     /// <https://dom.spec.whatwg.org/#connected>
     pub fn is_connected(&self) -> bool {
         let node = self.upcast::<Node>();
-        let root = node.GetRootNode();
+        let mut options = GetRootNodeOptions::empty();
+        options.composed = true; // shadow included.
+        let root = node.GetRootNode(&options);
         root.is::<Document>()
     }
 
diff --git a/components/script/dom/htmlscriptelement.rs b/components/script/dom/htmlscriptelement.rs
index 627cfc7e779..12399c3b58e 100644
--- a/components/script/dom/htmlscriptelement.rs
+++ b/components/script/dom/htmlscriptelement.rs
@@ -778,12 +778,12 @@ impl VirtualMethods for HTMLScriptElement {
         }
     }
 
-    fn bind_to_tree(&self, tree_in_doc: bool) {
+    fn bind_to_tree(&self, is_connected: bool) {
         if let Some(ref s) = self.super_type() {
-            s.bind_to_tree(tree_in_doc);
+            s.bind_to_tree(is_connected);
         }
 
-        if tree_in_doc && !self.parser_inserted.get() {
+        if is_connected && !self.parser_inserted.get() {
             let script = Trusted::new(self);
             document_from_node(self).add_delayed_task(task!(ScriptDelayedInitialize: move || {
                 script.root().prepare();
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index 4aa6f390b16..d27b6fad873 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -10,9 +10,12 @@ use crate::dom::bindings::codegen::Bindings::CharacterDataBinding::CharacterData
 use crate::dom::bindings::codegen::Bindings::DocumentBinding::DocumentMethods;
 use crate::dom::bindings::codegen::Bindings::ElementBinding::ElementMethods;
 use crate::dom::bindings::codegen::Bindings::HTMLCollectionBinding::HTMLCollectionMethods;
-use crate::dom::bindings::codegen::Bindings::NodeBinding::{NodeConstants, NodeMethods};
+use crate::dom::bindings::codegen::Bindings::NodeBinding::{
+    GetRootNodeOptions, NodeConstants, NodeMethods,
+};
 use crate::dom::bindings::codegen::Bindings::NodeListBinding::NodeListMethods;
 use crate::dom::bindings::codegen::Bindings::ProcessingInstructionBinding::ProcessingInstructionMethods;
+use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::ShadowRootBinding::ShadowRootMethods;
 use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use crate::dom::bindings::codegen::InheritTypes::DocumentFragmentTypeId;
 use crate::dom::bindings::codegen::UnionTypes::NodeOrString;
@@ -274,14 +277,23 @@ impl Node {
         let parent_in_doc = self.is_in_doc();
         let parent_in_shadow_tree = self.is_in_shadow_tree();
         for node in new_child.traverse_preorder() {
-            node.set_flag(NodeFlags::IS_IN_DOC, parent_in_doc);
-            node.set_flag(NodeFlags::IS_IN_SHADOW_TREE, parent_in_shadow_tree);
             if parent_in_shadow_tree {
-                node.set_owner_shadow_root(&*self.owner_shadow_root());
+                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());
+                }
             }
+            let is_connected = if let Some(element) = node.downcast::<Element>() {
+                element.is_connected()
+            } else {
+                false
+            };
+            node.set_flag(NodeFlags::IS_IN_DOC, parent_in_doc || is_connected);
+            node.set_flag(NodeFlags::IS_IN_SHADOW_TREE, parent_in_shadow_tree);
             // Out-of-document elements never have the descendants flag set.
             debug_assert!(!node.get_flag(NodeFlags::HAS_DIRTY_DESCENDANTS));
-            vtable_for(&&*node).bind_to_tree(parent_in_doc);
+            vtable_for(&&*node).bind_to_tree(is_connected);
         }
     }
 
@@ -2163,7 +2175,13 @@ impl NodeMethods for Node {
     }
 
     // https://dom.spec.whatwg.org/#dom-node-getrootnode
-    fn GetRootNode(&self) -> DomRoot<Node> {
+    fn GetRootNode(&self, options: &GetRootNodeOptions) -> DomRoot<Node> {
+        if options.composed {
+            if let Some(shadow_root) = self.owner_shadow_root.get() {
+                // shadow-including root.
+                return shadow_root.Host().upcast::<Node>().GetRootNode(options);
+            }
+        }
         self.inclusive_ancestors().last().unwrap()
     }
 
diff --git a/components/script/dom/shadowroot.rs b/components/script/dom/shadowroot.rs
index e543750e6da..a7a3bb693e5 100644
--- a/components/script/dom/shadowroot.rs
+++ b/components/script/dom/shadowroot.rs
@@ -4,6 +4,7 @@
 
 use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::ShadowRootBinding::ShadowRootMethods;
 use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::{self, ShadowRootMode};
+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};
@@ -12,6 +13,7 @@ use crate::dom::document::Document;
 use crate::dom::documentfragment::DocumentFragment;
 use crate::dom::documentorshadowroot::{DocumentOrShadowRoot, DocumentOrShadowRootImpl};
 use crate::dom::element::Element;
+use crate::dom::node::{Node, NodeFlags};
 use crate::dom::stylesheetlist::StyleSheetList;
 use crate::dom::window::Window;
 use dom_struct::dom_struct;
@@ -28,10 +30,15 @@ pub struct ShadowRoot {
 }
 
 impl ShadowRoot {
+    #[allow(unrooted_must_root)]
     fn new_inherited(host: &Element, document: &Document) -> ShadowRoot {
         let has_browsing_context = true;
+        let document_fragment = DocumentFragment::new_inherited(document);
+        document_fragment
+            .upcast::<Node>()
+            .set_flag(NodeFlags::IS_IN_SHADOW_TREE, true);
         ShadowRoot {
-            document_fragment: DocumentFragment::new_inherited(document),
+            document_fragment,
             document_or_shadow_root: DocumentOrShadowRootImpl::new(
                 document.window(),
                 has_browsing_context,
diff --git a/components/script/dom/webidls/Node.webidl b/components/script/dom/webidls/Node.webidl
index cddb776e416..479bec28a1f 100644
--- a/components/script/dom/webidls/Node.webidl
+++ b/components/script/dom/webidls/Node.webidl
@@ -32,7 +32,7 @@ interface Node : EventTarget {
   readonly attribute Document? ownerDocument;
 
   [Pure]
-  Node getRootNode();
+  Node getRootNode(optional GetRootNodeOptions options);
 
   [Pure]
   readonly attribute Node? parentNode;
@@ -92,3 +92,7 @@ interface Node : EventTarget {
   [CEReactions, Throws]
   Node removeChild(Node child);
 };
+
+dictionary GetRootNodeOptions {
+  boolean composed = false;
+};