diff --git a/components/script/dom/bindings/htmlconstructor.rs b/components/script/dom/bindings/htmlconstructor.rs
index 5654b52938b..a13b6fa9ecb 100644
--- a/components/script/dom/bindings/htmlconstructor.rs
+++ b/components/script/dom/bindings/htmlconstructor.rs
@@ -72,8 +72,8 @@ use crate::dom::bindings::conversions::DerivedFrom;
 use crate::dom::bindings::error::{Error, Fallible};
 use crate::dom::bindings::root::DomRoot;
 use crate::dom::create::create_native_html_element;
-use crate::dom::customelementregistry::ConstructionStackEntry;
-use crate::dom::element::{CustomElementState, Element, ElementCreator};
+use crate::dom::customelementregistry::{ConstructionStackEntry, CustomElementState};
+use crate::dom::element::{Element, ElementCreator};
 use crate::dom::htmlelement::HTMLElement;
 use crate::dom::window::Window;
 use crate::script_thread::ScriptThread;
diff --git a/components/script/dom/create.rs b/components/script/dom/create.rs
index 461e37a28de..6ffb38f753a 100644
--- a/components/script/dom/create.rs
+++ b/components/script/dom/create.rs
@@ -5,9 +5,11 @@
 use crate::dom::bindings::error::{report_pending_exception, throw_dom_exception};
 use crate::dom::bindings::reflector::DomObject;
 use crate::dom::bindings::root::DomRoot;
-use crate::dom::customelementregistry::{is_valid_custom_element_name, upgrade_element};
+use crate::dom::customelementregistry::{
+    is_valid_custom_element_name, upgrade_element, CustomElementState,
+};
 use crate::dom::document::Document;
-use crate::dom::element::{CustomElementCreationMode, CustomElementState, Element, ElementCreator};
+use crate::dom::element::{CustomElementCreationMode, Element, ElementCreator};
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmlanchorelement::HTMLAnchorElement;
 use crate::dom::htmlareaelement::HTMLAreaElement;
diff --git a/components/script/dom/customelementregistry.rs b/components/script/dom/customelementregistry.rs
index ff109f3c966..e1b3163bf4a 100644
--- a/components/script/dom/customelementregistry.rs
+++ b/components/script/dom/customelementregistry.rs
@@ -23,7 +23,7 @@ use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::bindings::str::DOMString;
 use crate::dom::document::Document;
 use crate::dom::domexception::{DOMErrorName, DOMException};
-use crate::dom::element::{CustomElementState, Element};
+use crate::dom::element::Element;
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmlelement::HTMLElement;
 use crate::dom::node::{document_from_node, window_from_node, Node, ShadowIncluding};
@@ -47,6 +47,21 @@ use std::ops::Deref;
 use std::ptr;
 use std::rc::Rc;
 
+/// <https://dom.spec.whatwg.org/#concept-element-custom-element-state>
+#[derive(Clone, Copy, Eq, JSTraceable, MallocSizeOf, PartialEq)]
+pub enum CustomElementState {
+    Undefined,
+    Failed,
+    Uncustomized,
+    Custom,
+}
+
+impl Default for CustomElementState {
+    fn default() -> CustomElementState {
+        CustomElementState::Uncustomized
+    }
+}
+
 /// <https://html.spec.whatwg.org/multipage/#customelementregistry>
 #[dom_struct]
 pub struct CustomElementRegistry {
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index ce4a3ac5268..a27af0f99b3 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -33,7 +33,7 @@ use crate::dom::bindings::xmlname::{
 use crate::dom::characterdata::CharacterData;
 use crate::dom::create::create_element;
 use crate::dom::customelementregistry::{
-    CallbackReaction, CustomElementDefinition, CustomElementReaction,
+    CallbackReaction, CustomElementDefinition, CustomElementReaction, CustomElementState,
 };
 use crate::dom::document::{Document, LayoutDocumentHelpers};
 use crate::dom::documentfragment::DocumentFragment;
@@ -166,13 +166,6 @@ pub struct Element {
     /// when it has exclusive access to the element.
     #[ignore_malloc_size_of = "bitflags defined in rust-selectors"]
     selector_flags: Cell<ElementSelectorFlags>,
-    /// <https://html.spec.whatwg.org/multipage/#custom-element-reaction-queue>
-    custom_element_reaction_queue: DomRefCell<Vec<CustomElementReaction>>,
-    /// <https://dom.spec.whatwg.org/#concept-element-custom-element-definition>
-    #[ignore_malloc_size_of = "Rc"]
-    custom_element_definition: DomRefCell<Option<Rc<CustomElementDefinition>>>,
-    /// <https://dom.spec.whatwg.org/#concept-element-custom-element-state>
-    custom_element_state: Cell<CustomElementState>,
     rare_data: Box<ElementRareData>,
 }
 
@@ -203,15 +196,6 @@ pub enum CustomElementCreationMode {
     Asynchronous,
 }
 
-/// <https://dom.spec.whatwg.org/#concept-element-custom-element-state>
-#[derive(Clone, Copy, Eq, JSTraceable, MallocSizeOf, PartialEq)]
-pub enum CustomElementState {
-    Undefined,
-    Failed,
-    Uncustomized,
-    Custom,
-}
-
 impl ElementCreator {
     pub fn is_parser_created(&self) -> bool {
         match *self {
@@ -305,9 +289,6 @@ impl Element {
             class_list: Default::default(),
             state: Cell::new(state),
             selector_flags: Cell::new(ElementSelectorFlags::empty()),
-            custom_element_reaction_queue: Default::default(),
-            custom_element_definition: Default::default(),
-            custom_element_state: Cell::new(CustomElementState::Uncustomized),
             rare_data: Default::default(),
         }
     }
@@ -349,45 +330,55 @@ impl Element {
     }
 
     pub fn set_custom_element_state(&self, state: CustomElementState) {
-        self.custom_element_state.set(state);
+        self.rare_data.custom_element_state.set(state);
     }
 
     pub fn get_custom_element_state(&self) -> CustomElementState {
-        self.custom_element_state.get()
+        self.rare_data.custom_element_state.get()
     }
 
     pub fn set_custom_element_definition(&self, definition: Rc<CustomElementDefinition>) {
-        *self.custom_element_definition.borrow_mut() = Some(definition);
+        *self.rare_data.custom_element_definition.borrow_mut() = Some(definition);
     }
 
     pub fn get_custom_element_definition(&self) -> Option<Rc<CustomElementDefinition>> {
-        (*self.custom_element_definition.borrow()).clone()
+        (*self.rare_data.custom_element_definition.borrow()).clone()
     }
 
     pub fn push_callback_reaction(&self, function: Rc<Function>, args: Box<[Heap<JSVal>]>) {
-        self.custom_element_reaction_queue
+        self.rare_data
+            .custom_element_reaction_queue
             .borrow_mut()
             .push(CustomElementReaction::Callback(function, args));
     }
 
     pub fn push_upgrade_reaction(&self, definition: Rc<CustomElementDefinition>) {
-        self.custom_element_reaction_queue
+        self.rare_data
+            .custom_element_reaction_queue
             .borrow_mut()
             .push(CustomElementReaction::Upgrade(definition));
     }
 
     pub fn clear_reaction_queue(&self) {
-        self.custom_element_reaction_queue.borrow_mut().clear();
+        self.rare_data
+            .custom_element_reaction_queue
+            .borrow_mut()
+            .clear();
     }
 
     pub fn invoke_reactions(&self) {
         // TODO: This is not spec compliant, as this will allow some reactions to be processed
         // after clear_reaction_queue has been called.
         rooted_vec!(let mut reactions);
-        while !self.custom_element_reaction_queue.borrow().is_empty() {
+        while !self
+            .rare_data
+            .custom_element_reaction_queue
+            .borrow()
+            .is_empty()
+        {
             mem::swap(
                 &mut *reactions,
-                &mut *self.custom_element_reaction_queue.borrow_mut(),
+                &mut *self.rare_data.custom_element_reaction_queue.borrow_mut(),
             );
             for reaction in reactions.iter() {
                 reaction.invoke(self);
diff --git a/components/script/dom/raredata.rs b/components/script/dom/raredata.rs
index 05383197da7..9ebf8e7d787 100644
--- a/components/script/dom/raredata.rs
+++ b/components/script/dom/raredata.rs
@@ -4,8 +4,13 @@
 
 use crate::dom::bindings::cell::DomRefCell;
 use crate::dom::bindings::root::MutNullableDom;
+use crate::dom::customelementregistry::{
+    CustomElementDefinition, CustomElementReaction, CustomElementState,
+};
 use crate::dom::mutationobserver::RegisteredObserver;
 use crate::dom::shadowroot::ShadowRoot;
+use std::cell::Cell;
+use std::rc::Rc;
 
 #[derive(Default, JSTraceable, MallocSizeOf)]
 #[must_root]
@@ -25,4 +30,11 @@ pub struct ElementRareData {
     /// XXX This is currently not exposed to web content. Only for
     ///     internal use.
     pub shadow_root: MutNullableDom<ShadowRoot>,
+    /// <https://html.spec.whatwg.org/multipage/#custom-element-reaction-queue>
+    pub custom_element_reaction_queue: DomRefCell<Vec<CustomElementReaction>>,
+    /// <https://dom.spec.whatwg.org/#concept-element-custom-element-definition>
+    #[ignore_malloc_size_of = "Rc"]
+    pub custom_element_definition: DomRefCell<Option<Rc<CustomElementDefinition>>>,
+    /// <https://dom.spec.whatwg.org/#concept-element-custom-element-state>
+    pub custom_element_state: Cell<CustomElementState>,
 }