diff --git a/components/script/dom/attr.rs b/components/script/dom/attr.rs
index ea97c1a294f..d18eed26f65 100644
--- a/components/script/dom/attr.rs
+++ b/components/script/dom/attr.rs
@@ -7,7 +7,7 @@ use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::AttrBinding::{self, AttrMethods};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::{Reflector, reflect_dom_object};
-use dom::bindings::root::{LayoutJS, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{LayoutJS, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::customelementregistry::CallbackReaction;
 use dom::element::{AttributeMutation, Element};
@@ -32,7 +32,7 @@ pub struct Attr {
     value: DOMRefCell<AttrValue>,
 
     /// the element that owns this attribute.
-    owner: MutNullableJS<Element>,
+    owner: MutNullableDom<Element>,
 }
 
 impl Attr {
@@ -52,7 +52,7 @@ impl Attr {
                 prefix: prefix,
             },
             value: DOMRefCell::new(value),
-            owner: MutNullableJS::new(owner),
+            owner: MutNullableDom::new(owner),
         }
     }
 
diff --git a/components/script/dom/bindings/root.rs b/components/script/dom/bindings/root.rs
index a7f4bb9e411..dbfe4023d63 100644
--- a/components/script/dom/bindings/root.rs
+++ b/components/script/dom/bindings/root.rs
@@ -298,15 +298,15 @@ impl<T: DomObject + PartialEq> PartialEq<T> for MutDom<T> {
 /// on `Dom<T>`.
 #[must_root]
 #[derive(JSTraceable)]
-pub struct MutNullableJS<T: DomObject> {
+pub struct MutNullableDom<T: DomObject> {
     ptr: UnsafeCell<Option<Dom<T>>>,
 }
 
-impl<T: DomObject> MutNullableJS<T> {
-    /// Create a new `MutNullableJS`.
-    pub fn new(initial: Option<&T>) -> MutNullableJS<T> {
+impl<T: DomObject> MutNullableDom<T> {
+    /// Create a new `MutNullableDom`.
+    pub fn new(initial: Option<&T>) -> MutNullableDom<T> {
         debug_assert!(thread_state::get().is_script());
-        MutNullableJS {
+        MutNullableDom {
             ptr: UnsafeCell::new(initial.map(Dom::from_ref)),
         }
     }
@@ -344,7 +344,7 @@ impl<T: DomObject> MutNullableJS<T> {
         }
     }
 
-    /// Set this `MutNullableJS` to the given value.
+    /// Set this `MutNullableDom` to the given value.
     pub fn set(&self, val: Option<&T>) {
         debug_assert!(thread_state::get().is_script());
         unsafe {
@@ -360,7 +360,7 @@ impl<T: DomObject> MutNullableJS<T> {
     }
 }
 
-impl<T: DomObject> PartialEq for MutNullableJS<T> {
+impl<T: DomObject> PartialEq for MutNullableDom<T> {
     fn eq(&self, other: &Self) -> bool {
         unsafe {
             *self.ptr.get() == *other.ptr.get()
@@ -368,7 +368,7 @@ impl<T: DomObject> PartialEq for MutNullableJS<T> {
     }
 }
 
-impl<'a, T: DomObject> PartialEq<Option<&'a T>> for MutNullableJS<T> {
+impl<'a, T: DomObject> PartialEq<Option<&'a T>> for MutNullableDom<T> {
     fn eq(&self, other: &Option<&T>) -> bool {
         unsafe {
             *self.ptr.get() == other.map(Dom::from_ref)
@@ -376,17 +376,17 @@ impl<'a, T: DomObject> PartialEq<Option<&'a T>> for MutNullableJS<T> {
     }
 }
 
-impl<T: DomObject> Default for MutNullableJS<T> {
+impl<T: DomObject> Default for MutNullableDom<T> {
     #[allow(unrooted_must_root)]
-    fn default() -> MutNullableJS<T> {
+    fn default() -> MutNullableDom<T> {
         debug_assert!(thread_state::get().is_script());
-        MutNullableJS {
+        MutNullableDom {
             ptr: UnsafeCell::new(None),
         }
     }
 }
 
-impl<T: DomObject> HeapSizeOf for MutNullableJS<T> {
+impl<T: DomObject> HeapSizeOf for MutNullableDom<T> {
     fn heap_size_of_children(&self) -> usize {
         // See comment on HeapSizeOf for Dom<T>.
         0
diff --git a/components/script/dom/bluetoothdevice.rs b/components/script/dom/bluetoothdevice.rs
index c07852f7853..d98a1ed42f5 100644
--- a/components/script/dom/bluetoothdevice.rs
+++ b/components/script/dom/bluetoothdevice.rs
@@ -12,7 +12,7 @@ use dom::bindings::error::Error;
 use dom::bindings::error::ErrorResult;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::bluetooth::{AsyncBluetoothListener, Bluetooth, response_async};
 use dom::bluetoothcharacteristicproperties::BluetoothCharacteristicProperties;
@@ -35,7 +35,7 @@ pub struct BluetoothDevice {
     eventtarget: EventTarget,
     id: DOMString,
     name: Option<DOMString>,
-    gatt: MutNullableJS<BluetoothRemoteGATTServer>,
+    gatt: MutNullableDom<BluetoothRemoteGATTServer>,
     context: Dom<Bluetooth>,
     attribute_instance_map: (DOMRefCell<HashMap<String, Dom<BluetoothRemoteGATTService>>>,
                              DOMRefCell<HashMap<String, Dom<BluetoothRemoteGATTCharacteristic>>>,
diff --git a/components/script/dom/client.rs b/components/script/dom/client.rs
index 872b23196e6..6ec88bd0cbd 100644
--- a/components/script/dom/client.rs
+++ b/components/script/dom/client.rs
@@ -5,7 +5,7 @@
 use dom::bindings::codegen::Bindings::ClientBinding::{ClientMethods, Wrap};
 use dom::bindings::codegen::Bindings::ClientBinding::FrameType;
 use dom::bindings::reflector::{Reflector, reflect_dom_object};
-use dom::bindings::root::{Root, MutNullableJS};
+use dom::bindings::root::{Root, MutNullableDom};
 use dom::bindings::str::{DOMString, USVString};
 use dom::serviceworker::ServiceWorker;
 use dom::window::Window;
@@ -17,7 +17,7 @@ use uuid::Uuid;
 #[dom_struct]
 pub struct Client {
     reflector_: Reflector,
-    active_worker: MutNullableJS<ServiceWorker>,
+    active_worker: MutNullableDom<ServiceWorker>,
     url: ServoUrl,
     frame_type: FrameType,
     #[ignore_heap_size_of = "Defined in uuid"]
diff --git a/components/script/dom/cssgroupingrule.rs b/components/script/dom/cssgroupingrule.rs
index f3a46223752..de5e59f2784 100644
--- a/components/script/dom/cssgroupingrule.rs
+++ b/components/script/dom/cssgroupingrule.rs
@@ -6,7 +6,7 @@ use dom::bindings::codegen::Bindings::CSSGroupingRuleBinding::CSSGroupingRuleMet
 use dom::bindings::error::{ErrorResult, Fallible};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::cssrule::CSSRule;
 use dom::cssrulelist::{CSSRuleList, RulesSource};
@@ -21,7 +21,7 @@ pub struct CSSGroupingRule {
     cssrule: CSSRule,
     #[ignore_heap_size_of = "Arc"]
     rules: Arc<Locked<StyleCssRules>>,
-    rulelist: MutNullableJS<CSSRuleList>,
+    rulelist: MutNullableDom<CSSRuleList>,
 }
 
 impl CSSGroupingRule {
@@ -30,7 +30,7 @@ impl CSSGroupingRule {
         CSSGroupingRule {
             cssrule: CSSRule::new_inherited(parent_stylesheet),
             rules: rules,
-            rulelist: MutNullableJS::new(None),
+            rulelist: MutNullableDom::new(None),
         }
     }
 
diff --git a/components/script/dom/csskeyframerule.rs b/components/script/dom/csskeyframerule.rs
index 0b8329ccf1b..17b5c7a63c4 100644
--- a/components/script/dom/csskeyframerule.rs
+++ b/components/script/dom/csskeyframerule.rs
@@ -5,7 +5,7 @@
 use dom::bindings::codegen::Bindings::CSSKeyframeRuleBinding::{self, CSSKeyframeRuleMethods};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::cssrule::{CSSRule, SpecificCSSRule};
 use dom::cssstyledeclaration::{CSSModificationAccess, CSSStyleDeclaration, CSSStyleOwner};
@@ -21,7 +21,7 @@ pub struct CSSKeyframeRule {
     cssrule: CSSRule,
     #[ignore_heap_size_of = "Arc"]
     keyframerule: Arc<Locked<Keyframe>>,
-    style_decl: MutNullableJS<CSSStyleDeclaration>,
+    style_decl: MutNullableDom<CSSStyleDeclaration>,
 }
 
 impl CSSKeyframeRule {
diff --git a/components/script/dom/csskeyframesrule.rs b/components/script/dom/csskeyframesrule.rs
index d699f15c0a0..280cd53fcf6 100644
--- a/components/script/dom/csskeyframesrule.rs
+++ b/components/script/dom/csskeyframesrule.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::CSSKeyframesRuleBinding::CSSKeyframesRuleM
 use dom::bindings::error::ErrorResult;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::csskeyframerule::CSSKeyframeRule;
 use dom::cssrule::{CSSRule, SpecificCSSRule};
@@ -26,7 +26,7 @@ pub struct CSSKeyframesRule {
     cssrule: CSSRule,
     #[ignore_heap_size_of = "Arc"]
     keyframesrule: Arc<Locked<KeyframesRule>>,
-    rulelist: MutNullableJS<CSSRuleList>,
+    rulelist: MutNullableDom<CSSRuleList>,
 }
 
 impl CSSKeyframesRule {
@@ -35,7 +35,7 @@ impl CSSKeyframesRule {
         CSSKeyframesRule {
             cssrule: CSSRule::new_inherited(parent_stylesheet),
             keyframesrule: keyframesrule,
-            rulelist: MutNullableJS::new(None),
+            rulelist: MutNullableDom::new(None),
         }
     }
 
diff --git a/components/script/dom/cssmediarule.rs b/components/script/dom/cssmediarule.rs
index 1dc4ce69a11..c77ed0b7563 100644
--- a/components/script/dom/cssmediarule.rs
+++ b/components/script/dom/cssmediarule.rs
@@ -7,7 +7,7 @@ use dom::bindings::codegen::Bindings::CSSMediaRuleBinding;
 use dom::bindings::codegen::Bindings::CSSMediaRuleBinding::CSSMediaRuleMethods;
 use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::cssconditionrule::CSSConditionRule;
 use dom::cssrule::SpecificCSSRule;
@@ -27,7 +27,7 @@ pub struct CSSMediaRule {
     cssconditionrule: CSSConditionRule,
     #[ignore_heap_size_of = "Arc"]
     mediarule: Arc<Locked<MediaRule>>,
-    medialist: MutNullableJS<MediaList>,
+    medialist: MutNullableDom<MediaList>,
 }
 
 impl CSSMediaRule {
@@ -38,7 +38,7 @@ impl CSSMediaRule {
         CSSMediaRule {
             cssconditionrule: CSSConditionRule::new_inherited(parent_stylesheet, list),
             mediarule: mediarule,
-            medialist: MutNullableJS::new(None),
+            medialist: MutNullableDom::new(None),
         }
     }
 
diff --git a/components/script/dom/cssrulelist.rs b/components/script/dom/cssrulelist.rs
index 4500405869e..8fdef21c4d0 100644
--- a/components/script/dom/cssrulelist.rs
+++ b/components/script/dom/cssrulelist.rs
@@ -7,7 +7,7 @@ use dom::bindings::codegen::Bindings::CSSRuleListBinding;
 use dom::bindings::codegen::Bindings::CSSRuleListBinding::CSSRuleListMethods;
 use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::csskeyframerule::CSSKeyframeRule;
 use dom::cssrule::CSSRule;
 use dom::cssstylesheet::CSSStyleSheet;
@@ -39,7 +39,7 @@ pub struct CSSRuleList {
     parent_stylesheet: Dom<CSSStyleSheet>,
     #[ignore_heap_size_of = "Arc"]
     rules: RulesSource,
-    dom_rules: DOMRefCell<Vec<MutNullableJS<CSSRule>>>
+    dom_rules: DOMRefCell<Vec<MutNullableDom<CSSRule>>>
 }
 
 pub enum RulesSource {
@@ -53,10 +53,10 @@ impl CSSRuleList {
         let guard = parent_stylesheet.shared_lock().read();
         let dom_rules = match rules {
             RulesSource::Rules(ref rules) => {
-                rules.read_with(&guard).0.iter().map(|_| MutNullableJS::new(None)).collect()
+                rules.read_with(&guard).0.iter().map(|_| MutNullableDom::new(None)).collect()
             }
             RulesSource::Keyframes(ref rules) => {
-                rules.read_with(&guard).keyframes.iter().map(|_| MutNullableJS::new(None)).collect()
+                rules.read_with(&guard).keyframes.iter().map(|_| MutNullableDom::new(None)).collect()
             }
         };
 
@@ -102,7 +102,7 @@ impl CSSRuleList {
 
         let parent_stylesheet = &*self.parent_stylesheet;
         let dom_rule = CSSRule::new_specific(&window, parent_stylesheet, new_rule);
-        self.dom_rules.borrow_mut().insert(index, MutNullableJS::new(Some(&*dom_rule)));
+        self.dom_rules.borrow_mut().insert(index, MutNullableDom::new(Some(&*dom_rule)));
         Ok((idx))
     }
 
@@ -170,7 +170,7 @@ impl CSSRuleList {
         if let RulesSource::Rules(..) = self.rules {
             panic!("Can only call append_lazy_rule with keyframes-backed CSSRules");
         }
-        self.dom_rules.borrow_mut().push(MutNullableJS::new(None));
+        self.dom_rules.borrow_mut().push(MutNullableDom::new(None));
     }
 }
 
diff --git a/components/script/dom/cssstylerule.rs b/components/script/dom/cssstylerule.rs
index 5004a4f909b..b8b99b8aef3 100644
--- a/components/script/dom/cssstylerule.rs
+++ b/components/script/dom/cssstylerule.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::CSSStyleRuleBinding::{self, CSSStyleRuleMe
 use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::cssrule::{CSSRule, SpecificCSSRule};
 use dom::cssstyledeclaration::{CSSModificationAccess, CSSStyleDeclaration, CSSStyleOwner};
@@ -27,7 +27,7 @@ pub struct CSSStyleRule {
     cssrule: CSSRule,
     #[ignore_heap_size_of = "Arc"]
     stylerule: Arc<Locked<StyleRule>>,
-    style_decl: MutNullableJS<CSSStyleDeclaration>,
+    style_decl: MutNullableDom<CSSStyleDeclaration>,
 }
 
 impl CSSStyleRule {
diff --git a/components/script/dom/cssstylesheet.rs b/components/script/dom/cssstylesheet.rs
index 26396c96439..2839708e607 100644
--- a/components/script/dom/cssstylesheet.rs
+++ b/components/script/dom/cssstylesheet.rs
@@ -7,7 +7,7 @@ use dom::bindings::codegen::Bindings::CSSStyleSheetBinding::CSSStyleSheetMethods
 use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
 use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::reflector::{reflect_dom_object, DomObject};
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::cssrulelist::{CSSRuleList, RulesSource};
 use dom::element::Element;
@@ -23,7 +23,7 @@ use style::stylesheets::Stylesheet as StyleStyleSheet;
 pub struct CSSStyleSheet {
     stylesheet: StyleSheet,
     owner: Dom<Element>,
-    rulelist: MutNullableJS<CSSRuleList>,
+    rulelist: MutNullableDom<CSSRuleList>,
     #[ignore_heap_size_of = "Arc"]
     style_stylesheet: Arc<StyleStyleSheet>,
     origin_clean: Cell<bool>,
@@ -38,7 +38,7 @@ impl CSSStyleSheet {
         CSSStyleSheet {
             stylesheet: StyleSheet::new_inherited(type_, href, title),
             owner: Dom::from_ref(owner),
-            rulelist: MutNullableJS::new(None),
+            rulelist: MutNullableDom::new(None),
             style_stylesheet: stylesheet,
             origin_clean: Cell::new(true),
         }
diff --git a/components/script/dom/dissimilaroriginwindow.rs b/components/script/dom/dissimilaroriginwindow.rs
index 174446b6098..ba1adf00c21 100644
--- a/components/script/dom/dissimilaroriginwindow.rs
+++ b/components/script/dom/dissimilaroriginwindow.rs
@@ -6,7 +6,7 @@ use dom::bindings::codegen::Bindings::DissimilarOriginWindowBinding;
 use dom::bindings::codegen::Bindings::DissimilarOriginWindowBinding::DissimilarOriginWindowMethods;
 use dom::bindings::error::{Error, ErrorResult};
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::bindings::structuredclone::StructuredCloneData;
 use dom::dissimilaroriginlocation::DissimilarOriginLocation;
@@ -40,7 +40,7 @@ pub struct DissimilarOriginWindow {
     window_proxy: Dom<WindowProxy>,
 
     /// The location of this window, initialized lazily.
-    location: MutNullableJS<DissimilarOriginLocation>,
+    location: MutNullableDom<DissimilarOriginLocation>,
 }
 
 impl DissimilarOriginWindow {
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 3075dcfc54d..49dfdb4230e 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -27,7 +27,7 @@ use dom::bindings::inheritance::{Castable, ElementTypeId, HTMLElementTypeId, Nod
 use dom::bindings::num::Finite;
 use dom::bindings::refcounted::{Trusted, TrustedPromise};
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{Dom, LayoutJS, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{Dom, LayoutJS, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::{DOMString, USVString};
 use dom::bindings::xmlname::{namespace_from_domstring, validate_and_extract, xml_name_type};
 use dom::bindings::xmlname::XMLName::InvalidXMLName;
@@ -224,7 +224,7 @@ impl ::style::stylesheets::StylesheetInDocument for StyleSheetInDocument {
 pub struct Document {
     node: Node,
     window: Dom<Window>,
-    implementation: MutNullableJS<DOMImplementation>,
+    implementation: MutNullableDom<DOMImplementation>,
     content_type: DOMString,
     last_modified: Option<String>,
     encoding: Cell<EncodingRef>,
@@ -239,28 +239,28 @@ pub struct Document {
     tag_map: DOMRefCell<HashMap<LocalName, Dom<HTMLCollection>>>,
     tagns_map: DOMRefCell<HashMap<QualName, Dom<HTMLCollection>>>,
     classes_map: DOMRefCell<HashMap<Vec<Atom>, Dom<HTMLCollection>>>,
-    images: MutNullableJS<HTMLCollection>,
-    embeds: MutNullableJS<HTMLCollection>,
-    links: MutNullableJS<HTMLCollection>,
-    forms: MutNullableJS<HTMLCollection>,
-    scripts: MutNullableJS<HTMLCollection>,
-    anchors: MutNullableJS<HTMLCollection>,
-    applets: MutNullableJS<HTMLCollection>,
+    images: MutNullableDom<HTMLCollection>,
+    embeds: MutNullableDom<HTMLCollection>,
+    links: MutNullableDom<HTMLCollection>,
+    forms: MutNullableDom<HTMLCollection>,
+    scripts: MutNullableDom<HTMLCollection>,
+    anchors: MutNullableDom<HTMLCollection>,
+    applets: MutNullableDom<HTMLCollection>,
     /// Lock use for style attributes and author-origin stylesheet objects in this document.
     /// Can be acquired once for accessing many objects.
     style_shared_lock: StyleSharedRwLock,
     /// List of stylesheets associated with nodes in this document. |None| if the list needs to be refreshed.
     stylesheets: DOMRefCell<StylesheetSet<StyleSheetInDocument>>,
-    stylesheet_list: MutNullableJS<StyleSheetList>,
+    stylesheet_list: MutNullableDom<StyleSheetList>,
     ready_state: Cell<DocumentReadyState>,
     /// Whether the DOMContentLoaded event has already been dispatched.
     domcontentloaded_dispatched: Cell<bool>,
     /// The element that has most recently requested focus for itself.
-    possibly_focused: MutNullableJS<Element>,
+    possibly_focused: MutNullableDom<Element>,
     /// The element that currently has the document focus context.
-    focused: MutNullableJS<Element>,
+    focused: MutNullableDom<Element>,
     /// The script element that is currently executing.
-    current_script: MutNullableJS<HTMLScriptElement>,
+    current_script: MutNullableDom<HTMLScriptElement>,
     /// https://html.spec.whatwg.org/multipage/#pending-parsing-blocking-script
     pending_parsing_blocking_script: DOMRefCell<Option<PendingScript>>,
     /// Number of stylesheets that block executing the next parser-inserted script
@@ -288,14 +288,14 @@ pub struct Document {
     /// Tracks all outstanding loads related to this document.
     loader: DOMRefCell<DocumentLoader>,
     /// The current active HTML parser, to allow resuming after interruptions.
-    current_parser: MutNullableJS<ServoParser>,
+    current_parser: MutNullableDom<ServoParser>,
     /// When we should kick off a reflow. This happens during parsing.
     reflow_timeout: Cell<Option<u64>>,
     /// The cached first `base` element with an `href` attribute.
-    base_element: MutNullableJS<HTMLBaseElement>,
+    base_element: MutNullableDom<HTMLBaseElement>,
     /// This field is set to the document itself for inert documents.
     /// https://html.spec.whatwg.org/multipage/#appropriate-template-contents-owner-document
-    appropriate_template_contents_owner_document: MutNullableJS<Document>,
+    appropriate_template_contents_owner_document: MutNullableDom<Document>,
     /// Information on elements needing restyle to ship over to the layout thread when the
     /// time comes.
     pending_restyles: DOMRefCell<HashMap<Dom<Element>, PendingRestyle>>,
@@ -323,7 +323,7 @@ pub struct Document {
     /// https://html.spec.whatwg.org/multipage/#dom-document-referrer
     referrer: Option<String>,
     /// https://html.spec.whatwg.org/multipage/#target-element
-    target_element: MutNullableJS<Element>,
+    target_element: MutNullableDom<Element>,
     /// https://w3c.github.io/uievents/#event-type-dblclick
     #[ignore_heap_size_of = "Defined in std"]
     last_click_info: DOMRefCell<Option<(Instant, Point2D<f32>)>>,
@@ -341,7 +341,7 @@ pub struct Document {
     /// See also: https://github.com/servo/servo/issues/10110
     dom_count: Cell<u32>,
     /// Entry node for fullscreen.
-    fullscreen_element: MutNullableJS<Element>,
+    fullscreen_element: MutNullableDom<Element>,
     /// Map from ID to set of form control elements that have that ID as
     /// their 'form' content attribute. Used to reset form controls
     /// whenever any element with the same ID as the form attribute
@@ -1112,7 +1112,7 @@ impl Document {
     pub fn handle_mouse_move_event(&self,
                                    js_runtime: *mut JSRuntime,
                                    client_point: Option<Point2D<f32>>,
-                                   prev_mouse_over_target: &MutNullableJS<Element>) {
+                                   prev_mouse_over_target: &MutNullableDom<Element>) {
         let client_point = match client_point {
             None => {
                 // If there's no point, there's no target under the mouse
@@ -2264,7 +2264,7 @@ impl Document {
                 //StyleSharedRwLock::new()
             },
             stylesheets: DOMRefCell::new(StylesheetSet::new()),
-            stylesheet_list: MutNullableJS::new(None),
+            stylesheet_list: MutNullableDom::new(None),
             ready_state: Cell::new(ready_state),
             domcontentloaded_dispatched: Cell::new(domcontentloaded_dispatched),
             possibly_focused: Default::default(),
@@ -2299,12 +2299,12 @@ impl Document {
             origin: origin,
             referrer: referrer,
             referrer_policy: Cell::new(referrer_policy),
-            target_element: MutNullableJS::new(None),
+            target_element: MutNullableDom::new(None),
             last_click_info: DOMRefCell::new(None),
             ignore_destructive_writes_counter: Default::default(),
             spurious_animation_frames: Cell::new(0),
             dom_count: Cell::new(1),
-            fullscreen_element: MutNullableJS::new(None),
+            fullscreen_element: MutNullableDom::new(None),
             form_id_listener_map: Default::default(),
         }
     }
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 03c09c36df8..66c1ac9cbb1 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -24,7 +24,7 @@ use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::inheritance::{Castable, ElementTypeId, HTMLElementTypeId, NodeTypeId};
 use dom::bindings::refcounted::{Trusted, TrustedPromise};
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{Dom, LayoutJS, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{Dom, LayoutJS, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::bindings::xmlname::{namespace_from_domstring, validate_and_extract, xml_name_type};
 use dom::bindings::xmlname::XMLName::InvalidXMLName;
@@ -136,8 +136,8 @@ pub struct Element {
     is: DOMRefCell<Option<LocalName>>,
     #[ignore_heap_size_of = "Arc"]
     style_attribute: DOMRefCell<Option<Arc<Locked<PropertyDeclarationBlock>>>>,
-    attr_list: MutNullableJS<NamedNodeMap>,
-    class_list: MutNullableJS<DOMTokenList>,
+    attr_list: MutNullableDom<NamedNodeMap>,
+    class_list: MutNullableDom<DOMTokenList>,
     state: Cell<ElementState>,
     /// These flags are set by the style system to indicate the that certain
     /// operations may require restyling this element or its descendants. The
diff --git a/components/script/dom/event.rs b/components/script/dom/event.rs
index 58c4a503c8e..c00ed9a0011 100644
--- a/components/script/dom/event.rs
+++ b/components/script/dom/event.rs
@@ -11,7 +11,7 @@ use dom::bindings::error::Fallible;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{Dom, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::eventtarget::{CompiledEventListener, EventTarget, ListenerPhase};
@@ -29,8 +29,8 @@ use time;
 #[dom_struct]
 pub struct Event {
     reflector_: Reflector,
-    current_target: MutNullableJS<EventTarget>,
-    target: MutNullableJS<EventTarget>,
+    current_target: MutNullableDom<EventTarget>,
+    target: MutNullableDom<EventTarget>,
     type_: DOMRefCell<Atom>,
     phase: Cell<EventPhase>,
     canceled: Cell<EventDefault>,
diff --git a/components/script/dom/filereader.rs b/components/script/dom/filereader.rs
index 6e72249748f..2e5721cc910 100644
--- a/components/script/dom/filereader.rs
+++ b/components/script/dom/filereader.rs
@@ -11,7 +11,7 @@ use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::bindings::trace::RootedTraceableBox;
 use dom::blob::Blob;
@@ -87,7 +87,7 @@ pub enum FileReaderResult {
 pub struct FileReader {
     eventtarget: EventTarget,
     ready_state: Cell<FileReaderReadyState>,
-    error: MutNullableJS<DOMException>,
+    error: MutNullableDom<DOMException>,
     result: DOMRefCell<Option<FileReaderResult>>,
     generation_id: Cell<GenerationId>,
 }
@@ -97,7 +97,7 @@ impl FileReader {
         FileReader {
             eventtarget: EventTarget::new_inherited(),
             ready_state: Cell::new(FileReaderReadyState::Empty),
-            error: MutNullableJS::new(None),
+            error: MutNullableDom::new(None),
             result: DOMRefCell::new(None),
             generation_id: Cell::new(GenerationId(0)),
         }
diff --git a/components/script/dom/focusevent.rs b/components/script/dom/focusevent.rs
index 0dbf3fc2f1e..10d78227aa2 100644
--- a/components/script/dom/focusevent.rs
+++ b/components/script/dom/focusevent.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::UIEventBinding::UIEventMethods;
 use dom::bindings::error::Fallible;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::reflect_dom_object;
-use dom::bindings::root::{MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::event::{EventBubbles, EventCancelable};
 use dom::eventtarget::EventTarget;
@@ -20,7 +20,7 @@ use std::default::Default;
 #[dom_struct]
 pub struct FocusEvent {
     uievent: UIEvent,
-    related_target: MutNullableJS<EventTarget>,
+    related_target: MutNullableDom<EventTarget>,
 }
 
 impl FocusEvent {
diff --git a/components/script/dom/globalscope.rs b/components/script/dom/globalscope.rs
index 16e47e0396f..e9854d4f991 100644
--- a/components/script/dom/globalscope.rs
+++ b/components/script/dom/globalscope.rs
@@ -10,7 +10,7 @@ use dom::bindings::conversions::root_from_object;
 use dom::bindings::error::{ErrorInfo, report_pending_exception};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::settings_stack::{AutoEntryScript, entry_global, incumbent_global};
 use dom::bindings::str::DOMString;
 use dom::crypto::Crypto;
@@ -58,7 +58,7 @@ use timers::{OneshotTimers, TimerCallback};
 #[dom_struct]
 pub struct GlobalScope {
     eventtarget: EventTarget,
-    crypto: MutNullableJS<Crypto>,
+    crypto: MutNullableDom<Crypto>,
     next_worker_id: Cell<WorkerId>,
 
     /// Pipeline id associated with this global.
diff --git a/components/script/dom/htmlanchorelement.rs b/components/script/dom/htmlanchorelement.rs
index 05065e07806..bd363e316c6 100644
--- a/components/script/dom/htmlanchorelement.rs
+++ b/components/script/dom/htmlanchorelement.rs
@@ -11,7 +11,7 @@ use dom::bindings::codegen::Bindings::HTMLAnchorElementBinding::HTMLAnchorElemen
 use dom::bindings::codegen::Bindings::MouseEventBinding::MouseEventMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::{DOMString, USVString};
 use dom::document::Document;
 use dom::domtokenlist::DOMTokenList;
@@ -37,7 +37,7 @@ use style::attr::AttrValue;
 #[dom_struct]
 pub struct HTMLAnchorElement {
     htmlelement: HTMLElement,
-    rel_list: MutNullableJS<DOMTokenList>,
+    rel_list: MutNullableDom<DOMTokenList>,
     url: DOMRefCell<Option<ServoUrl>>,
 }
 
diff --git a/components/script/dom/htmlareaelement.rs b/components/script/dom/htmlareaelement.rs
index 531752ac8f9..2ea9dfa4006 100644
--- a/components/script/dom/htmlareaelement.rs
+++ b/components/script/dom/htmlareaelement.rs
@@ -7,7 +7,7 @@ use dom::bindings::codegen::Bindings::DOMTokenListBinding::DOMTokenListMethods;
 use dom::bindings::codegen::Bindings::HTMLAreaElementBinding;
 use dom::bindings::codegen::Bindings::HTMLAreaElementBinding::HTMLAreaElementMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::domtokenlist::DOMTokenList;
@@ -217,7 +217,7 @@ impl Area {
 #[dom_struct]
 pub struct HTMLAreaElement {
     htmlelement: HTMLElement,
-    rel_list: MutNullableJS<DOMTokenList>,
+    rel_list: MutNullableDom<DOMTokenList>,
 }
 
 impl HTMLAreaElement {
diff --git a/components/script/dom/htmlbuttonelement.rs b/components/script/dom/htmlbuttonelement.rs
index 00aec8d5f2d..37997c93702 100755
--- a/components/script/dom/htmlbuttonelement.rs
+++ b/components/script/dom/htmlbuttonelement.rs
@@ -7,7 +7,7 @@ use dom::attr::Attr;
 use dom::bindings::codegen::Bindings::HTMLButtonElementBinding;
 use dom::bindings::codegen::Bindings::HTMLButtonElementBinding::HTMLButtonElementMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element};
@@ -42,7 +42,7 @@ enum ButtonType {
 pub struct HTMLButtonElement {
     htmlelement: HTMLElement,
     button_type: Cell<ButtonType>,
-    form_owner: MutNullableJS<HTMLFormElement>,
+    form_owner: MutNullableDom<HTMLFormElement>,
 }
 
 impl HTMLButtonElement {
diff --git a/components/script/dom/htmlcollection.rs b/components/script/dom/htmlcollection.rs
index c99e794a0e5..dd8a62617db 100644
--- a/components/script/dom/htmlcollection.rs
+++ b/components/script/dom/htmlcollection.rs
@@ -6,7 +6,7 @@ use dom::bindings::codegen::Bindings::HTMLCollectionBinding;
 use dom::bindings::codegen::Bindings::HTMLCollectionBinding::HTMLCollectionMethods;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::{Reflector, reflect_dom_object};
-use dom::bindings::root::{Dom, Root, MutNullableJS};
+use dom::bindings::root::{Dom, Root, MutNullableDom};
 use dom::bindings::str::DOMString;
 use dom::bindings::trace::JSTraceable;
 use dom::bindings::xmlname::namespace_from_domstring;
@@ -60,7 +60,7 @@ pub struct HTMLCollection {
     // the length of the collection, and a cursor into the collection.
     // FIXME: make the cached cursor element a weak pointer
     cached_version: Cell<u64>,
-    cached_cursor_element: MutNullableJS<Element>,
+    cached_cursor_element: MutNullableDom<Element>,
     cached_cursor_index: Cell<OptionU32>,
     cached_length: Cell<OptionU32>,
 }
@@ -74,7 +74,7 @@ impl HTMLCollection {
             filter: filter,
             // Default values for the cache
             cached_version: Cell::new(root.inclusive_descendants_version()),
-            cached_cursor_element: MutNullableJS::new(None),
+            cached_cursor_element: MutNullableDom::new(None),
             cached_cursor_index: Cell::new(OptionU32::none()),
             cached_length: Cell::new(OptionU32::none()),
         }
diff --git a/components/script/dom/htmlelement.rs b/components/script/dom/htmlelement.rs
index 946696863dc..7890cc5fa89 100644
--- a/components/script/dom/htmlelement.rs
+++ b/components/script/dom/htmlelement.rs
@@ -12,7 +12,7 @@ use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use dom::bindings::error::{Error, ErrorResult};
 use dom::bindings::inheritance::{ElementTypeId, HTMLElementTypeId, NodeTypeId};
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{Dom, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{Dom, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::cssstyledeclaration::{CSSModificationAccess, CSSStyleDeclaration, CSSStyleOwner};
 use dom::document::{Document, FocusType};
@@ -39,8 +39,8 @@ use style::element_state::*;
 #[dom_struct]
 pub struct HTMLElement {
     element: Element,
-    style_decl: MutNullableJS<CSSStyleDeclaration>,
-    dataset: MutNullableJS<DOMStringMap>,
+    style_decl: MutNullableDom<CSSStyleDeclaration>,
+    dataset: MutNullableDom<DOMStringMap>,
 }
 
 impl HTMLElement {
diff --git a/components/script/dom/htmlfieldsetelement.rs b/components/script/dom/htmlfieldsetelement.rs
index 37187c6def5..e935169c244 100644
--- a/components/script/dom/htmlfieldsetelement.rs
+++ b/components/script/dom/htmlfieldsetelement.rs
@@ -6,7 +6,7 @@ use dom::attr::Attr;
 use dom::bindings::codegen::Bindings::HTMLFieldSetElementBinding;
 use dom::bindings::codegen::Bindings::HTMLFieldSetElementBinding::HTMLFieldSetElementMethods;
 use dom::bindings::inheritance::{Castable, ElementTypeId, HTMLElementTypeId, NodeTypeId};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element};
 use dom::htmlcollection::{CollectionFilter, HTMLCollection};
@@ -24,7 +24,7 @@ use style::element_state::*;
 #[dom_struct]
 pub struct HTMLFieldSetElement {
     htmlelement: HTMLElement,
-    form_owner: MutNullableJS<HTMLFormElement>,
+    form_owner: MutNullableDom<HTMLFormElement>,
 }
 
 impl HTMLFieldSetElement {
diff --git a/components/script/dom/htmliframeelement.rs b/components/script/dom/htmliframeelement.rs
index cbff0beacc4..8e71609a451 100644
--- a/components/script/dom/htmliframeelement.rs
+++ b/components/script/dom/htmliframeelement.rs
@@ -21,7 +21,7 @@ use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{LayoutJS, MutNullableJS, Root};
+use dom::bindings::root::{LayoutJS, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::customevent::CustomEvent;
 use dom::document::Document;
@@ -88,7 +88,7 @@ pub struct HTMLIFrameElement {
     browsing_context_id: Cell<Option<BrowsingContextId>>,
     pipeline_id: Cell<Option<PipelineId>>,
     pending_pipeline_id: Cell<Option<PipelineId>>,
-    sandbox: MutNullableJS<DOMTokenList>,
+    sandbox: MutNullableDom<DOMTokenList>,
     sandbox_allowance: Cell<Option<SandboxAllowance>>,
     load_blocker: DOMRefCell<Option<LoadBlocker>>,
     visibility: Cell<bool>,
diff --git a/components/script/dom/htmlimageelement.rs b/components/script/dom/htmlimageelement.rs
index 48cb34d1a98..89873ffc4d8 100644
--- a/components/script/dom/htmlimageelement.rs
+++ b/components/script/dom/htmlimageelement.rs
@@ -17,7 +17,7 @@ use dom::bindings::error::Fallible;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{LayoutJS, MutNullableJS, Root};
+use dom::bindings::root::{LayoutJS, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element, RawLayoutElementHelpers};
@@ -89,7 +89,7 @@ pub struct HTMLImageElement {
     image_request: Cell<ImageRequestPhase>,
     current_request: DOMRefCell<ImageRequest>,
     pending_request: DOMRefCell<ImageRequest>,
-    form_owner: MutNullableJS<HTMLFormElement>,
+    form_owner: MutNullableDom<HTMLFormElement>,
     generation: Cell<u32>,
 }
 
diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index 2cb872e4908..bd714509dda 100755
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -15,7 +15,7 @@ use dom::bindings::codegen::Bindings::MouseEventBinding::MouseEventMethods;
 use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use dom::bindings::error::{Error, ErrorResult};
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{Dom, LayoutJS, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{Dom, LayoutJS, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element, LayoutElementHelpers, RawLayoutElementHelpers};
@@ -99,8 +99,8 @@ pub struct HTMLInputElement {
     // https://html.spec.whatwg.org/multipage/#concept-input-value-dirty-flag
     value_dirty: Cell<bool>,
 
-    filelist: MutNullableJS<FileList>,
-    form_owner: MutNullableJS<HTMLFormElement>,
+    filelist: MutNullableDom<FileList>,
+    form_owner: MutNullableDom<HTMLFormElement>,
 }
 
 #[derive(JSTraceable)]
@@ -156,7 +156,7 @@ impl HTMLInputElement {
                                                       SelectionDirection::None)),
             activation_state: DOMRefCell::new(InputActivationState::new()),
             value_dirty: Cell::new(false),
-            filelist: MutNullableJS::new(None),
+            filelist: MutNullableDom::new(None),
             form_owner: Default::default(),
         }
     }
diff --git a/components/script/dom/htmllegendelement.rs b/components/script/dom/htmllegendelement.rs
index ad51e0cb652..010e80c22ee 100644
--- a/components/script/dom/htmllegendelement.rs
+++ b/components/script/dom/htmllegendelement.rs
@@ -6,7 +6,7 @@ use dom::bindings::codegen::Bindings::HTMLLegendElementBinding;
 use dom::bindings::codegen::Bindings::HTMLLegendElementBinding::HTMLLegendElementMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::document::Document;
 use dom::element::Element;
 use dom::htmlelement::HTMLElement;
@@ -20,7 +20,7 @@ use html5ever::{LocalName, Prefix};
 #[dom_struct]
 pub struct HTMLLegendElement {
     htmlelement: HTMLElement,
-    form_owner: MutNullableJS<HTMLFormElement>,
+    form_owner: MutNullableDom<HTMLFormElement>,
 }
 
 impl HTMLLegendElement {
diff --git a/components/script/dom/htmllinkelement.rs b/components/script/dom/htmllinkelement.rs
index 814c6b94bd4..b229e331ed6 100644
--- a/components/script/dom/htmllinkelement.rs
+++ b/components/script/dom/htmllinkelement.rs
@@ -9,7 +9,7 @@ use dom::bindings::codegen::Bindings::DOMTokenListBinding::DOMTokenListBinding::
 use dom::bindings::codegen::Bindings::HTMLLinkElementBinding;
 use dom::bindings::codegen::Bindings::HTMLLinkElementBinding::HTMLLinkElementMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::cssstylesheet::CSSStyleSheet;
 use dom::document::Document;
@@ -50,10 +50,10 @@ impl RequestGenerationId {
 #[dom_struct]
 pub struct HTMLLinkElement {
     htmlelement: HTMLElement,
-    rel_list: MutNullableJS<DOMTokenList>,
+    rel_list: MutNullableDom<DOMTokenList>,
     #[ignore_heap_size_of = "Arc"]
     stylesheet: DOMRefCell<Option<Arc<Stylesheet>>>,
-    cssom_stylesheet: MutNullableJS<CSSStyleSheet>,
+    cssom_stylesheet: MutNullableDom<CSSStyleSheet>,
 
     /// https://html.spec.whatwg.org/multipage/#a-style-sheet-that-is-blocking-scripts
     parser_inserted: Cell<bool>,
@@ -74,7 +74,7 @@ impl HTMLLinkElement {
             rel_list: Default::default(),
             parser_inserted: Cell::new(creator.is_parser_created()),
             stylesheet: DOMRefCell::new(None),
-            cssom_stylesheet: MutNullableJS::new(None),
+            cssom_stylesheet: MutNullableDom::new(None),
             pending_loads: Cell::new(0),
             any_failed_load: Cell::new(false),
             request_generation_id: Cell::new(RequestGenerationId(0)),
diff --git a/components/script/dom/htmlmediaelement.rs b/components/script/dom/htmlmediaelement.rs
index cadde0b2073..81708864742 100644
--- a/components/script/dom/htmlmediaelement.rs
+++ b/components/script/dom/htmlmediaelement.rs
@@ -18,7 +18,7 @@ use dom::bindings::error::{Error, ErrorResult};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{Element, AttributeMutation};
@@ -66,7 +66,7 @@ pub struct HTMLMediaElement {
     /// Reset to false every time the load algorithm is invoked.
     fired_loadeddata_event: Cell<bool>,
     /// https://html.spec.whatwg.org/multipage/#dom-media-error
-    error: MutNullableJS<MediaError>,
+    error: MutNullableDom<MediaError>,
     /// https://html.spec.whatwg.org/multipage/#dom-media-paused
     paused: Cell<bool>,
     /// https://html.spec.whatwg.org/multipage/#attr-media-autoplay
diff --git a/components/script/dom/htmlmetaelement.rs b/components/script/dom/htmlmetaelement.rs
index 09443824b70..41ae52a1b4c 100644
--- a/components/script/dom/htmlmetaelement.rs
+++ b/components/script/dom/htmlmetaelement.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::HTMLMetaElementBinding;
 use dom::bindings::codegen::Bindings::HTMLMetaElementBinding::HTMLMetaElementMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::cssstylesheet::CSSStyleSheet;
 use dom::document::Document;
@@ -34,7 +34,7 @@ pub struct HTMLMetaElement {
     htmlelement: HTMLElement,
     #[ignore_heap_size_of = "Arc"]
     stylesheet: DOMRefCell<Option<Arc<Stylesheet>>>,
-    cssom_stylesheet: MutNullableJS<CSSStyleSheet>,
+    cssom_stylesheet: MutNullableDom<CSSStyleSheet>,
 }
 
 impl HTMLMetaElement {
@@ -44,7 +44,7 @@ impl HTMLMetaElement {
         HTMLMetaElement {
             htmlelement: HTMLElement::new_inherited(local_name, prefix, document),
             stylesheet: DOMRefCell::new(None),
-            cssom_stylesheet: MutNullableJS::new(None),
+            cssom_stylesheet: MutNullableDom::new(None),
         }
     }
 
diff --git a/components/script/dom/htmlobjectelement.rs b/components/script/dom/htmlobjectelement.rs
index bfab288a9cf..121dde5d2ae 100755
--- a/components/script/dom/htmlobjectelement.rs
+++ b/components/script/dom/htmlobjectelement.rs
@@ -7,7 +7,7 @@ use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::HTMLObjectElementBinding;
 use dom::bindings::codegen::Bindings::HTMLObjectElementBinding::HTMLObjectElementMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element};
@@ -28,7 +28,7 @@ pub struct HTMLObjectElement {
     htmlelement: HTMLElement,
     #[ignore_heap_size_of = "Arc"]
     image: DOMRefCell<Option<Arc<Image>>>,
-    form_owner: MutNullableJS<HTMLFormElement>,
+    form_owner: MutNullableDom<HTMLFormElement>,
 }
 
 impl HTMLObjectElement {
diff --git a/components/script/dom/htmloutputelement.rs b/components/script/dom/htmloutputelement.rs
index 510235e617a..2a52cfabcaa 100644
--- a/components/script/dom/htmloutputelement.rs
+++ b/components/script/dom/htmloutputelement.rs
@@ -6,7 +6,7 @@ use dom::attr::Attr;
 use dom::bindings::codegen::Bindings::HTMLOutputElementBinding;
 use dom::bindings::codegen::Bindings::HTMLOutputElementBinding::HTMLOutputElementMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element};
 use dom::htmlelement::HTMLElement;
@@ -21,7 +21,7 @@ use html5ever::{LocalName, Prefix};
 #[dom_struct]
 pub struct HTMLOutputElement {
     htmlelement: HTMLElement,
-    form_owner: MutNullableJS<HTMLFormElement>,
+    form_owner: MutNullableDom<HTMLFormElement>,
 }
 
 impl HTMLOutputElement {
diff --git a/components/script/dom/htmlselectelement.rs b/components/script/dom/htmlselectelement.rs
index 641a8817814..73238870e48 100755
--- a/components/script/dom/htmlselectelement.rs
+++ b/components/script/dom/htmlselectelement.rs
@@ -14,7 +14,7 @@ use dom::bindings::codegen::UnionTypes::HTMLElementOrLong;
 use dom::bindings::codegen::UnionTypes::HTMLOptionElementOrHTMLOptGroupElement;
 //use dom::bindings::error::ErrorResult;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element};
@@ -61,8 +61,8 @@ impl CollectionFilter for OptionsFilter {
 #[dom_struct]
 pub struct HTMLSelectElement {
     htmlelement: HTMLElement,
-    options: MutNullableJS<HTMLOptionsCollection>,
-    form_owner: MutNullableJS<HTMLFormElement>,
+    options: MutNullableDom<HTMLOptionsCollection>,
+    form_owner: MutNullableDom<HTMLFormElement>,
 }
 
 static DEFAULT_SELECT_SIZE: u32 = 0;
diff --git a/components/script/dom/htmlstyleelement.rs b/components/script/dom/htmlstyleelement.rs
index cfe0651df28..a66ede9c930 100644
--- a/components/script/dom/htmlstyleelement.rs
+++ b/components/script/dom/htmlstyleelement.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::HTMLStyleElementBinding;
 use dom::bindings::codegen::Bindings::HTMLStyleElementBinding::HTMLStyleElementMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::cssstylesheet::CSSStyleSheet;
 use dom::document::Document;
 use dom::element::{Element, ElementCreator};
@@ -33,7 +33,7 @@ pub struct HTMLStyleElement {
     htmlelement: HTMLElement,
     #[ignore_heap_size_of = "Arc"]
     stylesheet: DOMRefCell<Option<Arc<Stylesheet>>>,
-    cssom_stylesheet: MutNullableJS<CSSStyleSheet>,
+    cssom_stylesheet: MutNullableDom<CSSStyleSheet>,
     /// https://html.spec.whatwg.org/multipage/#a-style-sheet-that-is-blocking-scripts
     parser_inserted: Cell<bool>,
     in_stack_of_open_elements: Cell<bool>,
@@ -50,7 +50,7 @@ impl HTMLStyleElement {
         HTMLStyleElement {
             htmlelement: HTMLElement::new_inherited(local_name, prefix, document),
             stylesheet: DOMRefCell::new(None),
-            cssom_stylesheet: MutNullableJS::new(None),
+            cssom_stylesheet: MutNullableDom::new(None),
             parser_inserted: Cell::new(creator.is_parser_created()),
             in_stack_of_open_elements: Cell::new(creator.is_parser_created()),
             pending_loads: Cell::new(0),
diff --git a/components/script/dom/htmltableelement.rs b/components/script/dom/htmltableelement.rs
index 5e9a80f0790..25069647f6c 100644
--- a/components/script/dom/htmltableelement.rs
+++ b/components/script/dom/htmltableelement.rs
@@ -10,7 +10,7 @@ use dom::bindings::codegen::Bindings::HTMLTableElementBinding::HTMLTableElementM
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{Dom, LayoutJS, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{Dom, LayoutJS, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element, RawLayoutElementHelpers};
@@ -32,7 +32,7 @@ pub struct HTMLTableElement {
     htmlelement: HTMLElement,
     border: Cell<Option<u32>>,
     cellspacing: Cell<Option<u32>>,
-    tbodies: MutNullableJS<HTMLCollection>,
+    tbodies: MutNullableDom<HTMLCollection>,
 }
 
 #[allow(unrooted_must_root)]
diff --git a/components/script/dom/htmltablerowelement.rs b/components/script/dom/htmltablerowelement.rs
index c56c7ae7add..78246d4444c 100644
--- a/components/script/dom/htmltablerowelement.rs
+++ b/components/script/dom/htmltablerowelement.rs
@@ -9,7 +9,7 @@ use dom::bindings::codegen::Bindings::HTMLTableSectionElementBinding::HTMLTableS
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::error::{ErrorResult, Fallible};
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{LayoutJS, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{LayoutJS, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{Element, RawLayoutElementHelpers};
@@ -37,7 +37,7 @@ impl CollectionFilter for CellsFilter {
 #[dom_struct]
 pub struct HTMLTableRowElement {
     htmlelement: HTMLElement,
-    cells: MutNullableJS<HTMLCollection>,
+    cells: MutNullableDom<HTMLCollection>,
 }
 
 impl HTMLTableRowElement {
diff --git a/components/script/dom/htmltemplateelement.rs b/components/script/dom/htmltemplateelement.rs
index ec46955db7e..5f345206a94 100644
--- a/components/script/dom/htmltemplateelement.rs
+++ b/components/script/dom/htmltemplateelement.rs
@@ -7,7 +7,7 @@ use dom::bindings::codegen::Bindings::HTMLTemplateElementBinding;
 use dom::bindings::codegen::Bindings::HTMLTemplateElementBinding::HTMLTemplateElementMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::document::Document;
 use dom::documentfragment::DocumentFragment;
 use dom::htmlelement::HTMLElement;
@@ -21,7 +21,7 @@ pub struct HTMLTemplateElement {
     htmlelement: HTMLElement,
 
     /// https://html.spec.whatwg.org/multipage/#template-contents
-    contents: MutNullableJS<DocumentFragment>,
+    contents: MutNullableDom<DocumentFragment>,
 }
 
 impl HTMLTemplateElement {
@@ -31,7 +31,7 @@ impl HTMLTemplateElement {
         HTMLTemplateElement {
             htmlelement:
                 HTMLElement::new_inherited(local_name, prefix, document),
-            contents: MutNullableJS::new(None),
+            contents: MutNullableDom::new(None),
         }
     }
 
diff --git a/components/script/dom/htmltextareaelement.rs b/components/script/dom/htmltextareaelement.rs
index 9c050f0790f..4958d2d3ca9 100755
--- a/components/script/dom/htmltextareaelement.rs
+++ b/components/script/dom/htmltextareaelement.rs
@@ -9,7 +9,7 @@ use dom::bindings::codegen::Bindings::HTMLTextAreaElementBinding;
 use dom::bindings::codegen::Bindings::HTMLTextAreaElementBinding::HTMLTextAreaElementMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::root::{LayoutJS, MutNullableJS, Root};
+use dom::bindings::root::{LayoutJS, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element};
@@ -43,7 +43,7 @@ pub struct HTMLTextAreaElement {
     placeholder: DOMRefCell<DOMString>,
     // https://html.spec.whatwg.org/multipage/#concept-textarea-dirty
     value_changed: Cell<bool>,
-    form_owner: MutNullableJS<HTMLFormElement>,
+    form_owner: MutNullableDom<HTMLFormElement>,
 }
 
 pub trait LayoutHTMLTextAreaElementHelpers {
diff --git a/components/script/dom/mod.rs b/components/script/dom/mod.rs
index 7c683edf9eb..b14cca5f820 100644
--- a/components/script/dom/mod.rs
+++ b/components/script/dom/mod.rs
@@ -32,7 +32,7 @@
 //! * rooting pointers on the stack:
 //!   the [`Root`](bindings/root/struct.Root.html) smart pointer;
 //! * tracing pointers in member fields: the [`Dom`](bindings/root/struct.Dom.html),
-//!   [`MutNullableJS`](bindings/root/struct.MutNullableJS.html) and
+//!   [`MutNullableDom`](bindings/root/struct.MutNullableDom.html) and
 //!   [`MutDom`](bindings/root/struct.MutDom.html) smart pointers and
 //!   [the tracing implementation](bindings/trace/index.html);
 //! * rooting pointers from across thread boundaries or in channels: the
diff --git a/components/script/dom/mouseevent.rs b/components/script/dom/mouseevent.rs
index 049a92c8308..e3f4cdab91d 100644
--- a/components/script/dom/mouseevent.rs
+++ b/components/script/dom/mouseevent.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::UIEventBinding::UIEventMethods;
 use dom::bindings::error::Fallible;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::reflect_dom_object;
-use dom::bindings::root::{MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::event::{Event, EventBubbles, EventCancelable};
 use dom::eventtarget::EventTarget;
@@ -31,7 +31,7 @@ pub struct MouseEvent {
     alt_key: Cell<bool>,
     meta_key: Cell<bool>,
     button: Cell<i16>,
-    related_target: MutNullableJS<EventTarget>,
+    related_target: MutNullableDom<EventTarget>,
 }
 
 impl MouseEvent {
diff --git a/components/script/dom/mutationrecord.rs b/components/script/dom/mutationrecord.rs
index a5d21663b99..bbb42dd1f28 100644
--- a/components/script/dom/mutationrecord.rs
+++ b/components/script/dom/mutationrecord.rs
@@ -5,7 +5,7 @@
 use dom::bindings::codegen::Bindings::MutationRecordBinding::MutationRecordBinding;
 use dom::bindings::codegen::Bindings::MutationRecordBinding::MutationRecordBinding::MutationRecordMethods;
 use dom::bindings::reflector::{Reflector, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::node::{Node, window_from_node};
 use dom::nodelist::NodeList;
@@ -20,8 +20,8 @@ pub struct MutationRecord {
     attribute_name: Option<DOMString>,
     attribute_namespace: Option<DOMString>,
     old_value: Option<DOMString>,
-    added_nodes: MutNullableJS<NodeList>,
-    removed_nodes: MutNullableJS<NodeList>,
+    added_nodes: MutNullableDom<NodeList>,
+    removed_nodes: MutNullableDom<NodeList>,
     next_sibling: Option<Dom<Node>>,
     prev_sibling: Option<Dom<Node>>,
 }
@@ -77,8 +77,8 @@ impl MutationRecord {
             attribute_name: attribute_name,
             attribute_namespace: attribute_namespace,
             old_value: old_value,
-            added_nodes: MutNullableJS::new(added_nodes),
-            removed_nodes: MutNullableJS::new(removed_nodes),
+            added_nodes: MutNullableDom::new(added_nodes),
+            removed_nodes: MutNullableDom::new(removed_nodes),
             next_sibling: next_sibling.map(Dom::from_ref),
             prev_sibling: prev_sibling.map(Dom::from_ref),
         }
diff --git a/components/script/dom/navigator.rs b/components/script/dom/navigator.rs
index dddac1bb561..c24b4972e37 100644
--- a/components/script/dom/navigator.rs
+++ b/components/script/dom/navigator.rs
@@ -6,7 +6,7 @@ use dom::bindings::codegen::Bindings::NavigatorBinding;
 use dom::bindings::codegen::Bindings::NavigatorBinding::NavigatorMethods;
 use dom::bindings::codegen::Bindings::VRBinding::VRBinding::VRMethods;
 use dom::bindings::reflector::{Reflector, DomObject, reflect_dom_object};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::bluetooth::Bluetooth;
 use dom::gamepadlist::GamepadList;
@@ -24,13 +24,13 @@ use std::rc::Rc;
 #[dom_struct]
 pub struct Navigator {
     reflector_: Reflector,
-    bluetooth: MutNullableJS<Bluetooth>,
-    plugins: MutNullableJS<PluginArray>,
-    mime_types: MutNullableJS<MimeTypeArray>,
-    service_worker: MutNullableJS<ServiceWorkerContainer>,
-    vr: MutNullableJS<VR>,
-    gamepads: MutNullableJS<GamepadList>,
-    permissions: MutNullableJS<Permissions>,
+    bluetooth: MutNullableDom<Bluetooth>,
+    plugins: MutNullableDom<PluginArray>,
+    mime_types: MutNullableDom<MimeTypeArray>,
+    service_worker: MutNullableDom<ServiceWorkerContainer>,
+    vr: MutNullableDom<VR>,
+    gamepads: MutNullableDom<GamepadList>,
+    permissions: MutNullableDom<Permissions>,
 }
 
 impl Navigator {
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index f3cf9728b72..2ce11daeb0f 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -23,7 +23,7 @@ use dom::bindings::inheritance::{Castable, CharacterDataTypeId, ElementTypeId};
 use dom::bindings::inheritance::{EventTargetTypeId, HTMLElementTypeId, NodeTypeId};
 use dom::bindings::inheritance::{SVGElementTypeId, SVGGraphicsElementTypeId};
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{Dom, LayoutJS, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{Dom, LayoutJS, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::{DOMString, USVString};
 use dom::bindings::xmlname::namespace_from_domstring;
 use dom::characterdata::{CharacterData, LayoutCharacterDataHelpers};
@@ -98,25 +98,25 @@ pub struct Node {
     eventtarget: EventTarget,
 
     /// The parent of this node.
-    parent_node: MutNullableJS<Node>,
+    parent_node: MutNullableDom<Node>,
 
     /// The first child of this node.
-    first_child: MutNullableJS<Node>,
+    first_child: MutNullableDom<Node>,
 
     /// The last child of this node.
-    last_child: MutNullableJS<Node>,
+    last_child: MutNullableDom<Node>,
 
     /// The next sibling of this node.
-    next_sibling: MutNullableJS<Node>,
+    next_sibling: MutNullableDom<Node>,
 
     /// The previous sibling of this node.
-    prev_sibling: MutNullableJS<Node>,
+    prev_sibling: MutNullableDom<Node>,
 
     /// The document that this node belongs to.
-    owner_doc: MutNullableJS<Document>,
+    owner_doc: MutNullableDom<Document>,
 
     /// The live list of children return by .childNodes.
-    child_list: MutNullableJS<NodeList>,
+    child_list: MutNullableDom<NodeList>,
 
     /// The live count of children of this node.
     children_count: Cell<u32>,
@@ -1407,7 +1407,7 @@ impl Node {
             last_child: Default::default(),
             next_sibling: Default::default(),
             prev_sibling: Default::default(),
-            owner_doc: MutNullableJS::new(doc),
+            owner_doc: MutNullableDom::new(doc),
             child_list: Default::default(),
             children_count: Cell::new(0u32),
             flags: Cell::new(flags),
diff --git a/components/script/dom/nodelist.rs b/components/script/dom/nodelist.rs
index 14d1e533ef5..191cc1f30cd 100644
--- a/components/script/dom/nodelist.rs
+++ b/components/script/dom/nodelist.rs
@@ -6,7 +6,7 @@ use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::codegen::Bindings::NodeListBinding;
 use dom::bindings::codegen::Bindings::NodeListBinding::NodeListMethods;
 use dom::bindings::reflector::{Reflector, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{Dom, MutNullableDom, Root, RootedReference};
 use dom::node::{ChildrenMutation, Node};
 use dom::window::Window;
 use dom_struct::dom_struct;
@@ -114,7 +114,7 @@ impl NodeList {
 pub struct ChildrenList {
     node: Dom<Node>,
     #[ignore_heap_size_of = "Defined in rust-mozjs"]
-    last_visited: MutNullableJS<Node>,
+    last_visited: MutNullableDom<Node>,
     last_index: Cell<u32>,
 }
 
@@ -123,7 +123,7 @@ impl ChildrenList {
         let last_visited = node.GetFirstChild();
         ChildrenList {
             node: Dom::from_ref(node),
-            last_visited: MutNullableJS::new(last_visited.r()),
+            last_visited: MutNullableDom::new(last_visited.r()),
             last_index: Cell::new(0u32),
         }
     }
diff --git a/components/script/dom/request.rs b/components/script/dom/request.rs
index 1225369cea5..1d9d20629d0 100644
--- a/components/script/dom/request.rs
+++ b/components/script/dom/request.rs
@@ -18,7 +18,7 @@ use dom::bindings::codegen::Bindings::RequestBinding::RequestRedirect;
 use dom::bindings::codegen::Bindings::RequestBinding::RequestType;
 use dom::bindings::error::{Error, Fallible};
 use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::{ByteString, DOMString, USVString};
 use dom::bindings::trace::RootedTraceableBox;
 use dom::globalscope::GlobalScope;
@@ -46,7 +46,7 @@ pub struct Request {
     reflector_: Reflector,
     request: DOMRefCell<NetTraitsRequest>,
     body_used: Cell<bool>,
-    headers: MutNullableJS<Headers>,
+    headers: MutNullableDom<Headers>,
     mime_type: DOMRefCell<Vec<u8>>,
     #[ignore_heap_size_of = "Rc"]
     body_promise: DOMRefCell<Option<(Rc<Promise>, BodyType)>>,
diff --git a/components/script/dom/response.rs b/components/script/dom/response.rs
index 5d254b34525..55c942e88fc 100644
--- a/components/script/dom/response.rs
+++ b/components/script/dom/response.rs
@@ -11,7 +11,7 @@ use dom::bindings::codegen::Bindings::ResponseBinding::{ResponseMethods, Respons
 use dom::bindings::codegen::Bindings::XMLHttpRequestBinding::BodyInit;
 use dom::bindings::error::{Error, Fallible};
 use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::{ByteString, USVString};
 use dom::globalscope::GlobalScope;
 use dom::headers::{Headers, Guard};
@@ -33,7 +33,7 @@ use url::Position;
 #[dom_struct]
 pub struct Response {
     reflector_: Reflector,
-    headers_reflector: MutNullableJS<Headers>,
+    headers_reflector: MutNullableDom<Headers>,
     mime_type: DOMRefCell<Vec<u8>>,
     body_used: Cell<bool>,
     /// `None` can be considered a StatusCode of `0`.
diff --git a/components/script/dom/serviceworkercontainer.rs b/components/script/dom/serviceworkercontainer.rs
index a322f618fa8..e4cb7c3a255 100644
--- a/components/script/dom/serviceworkercontainer.rs
+++ b/components/script/dom/serviceworkercontainer.rs
@@ -6,7 +6,7 @@ use dom::bindings::codegen::Bindings::ServiceWorkerContainerBinding::{ServiceWor
 use dom::bindings::codegen::Bindings::ServiceWorkerContainerBinding::RegistrationOptions;
 use dom::bindings::error::Error;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::bindings::str::USVString;
 use dom::client::Client;
 use dom::eventtarget::EventTarget;
@@ -23,7 +23,7 @@ use std::rc::Rc;
 #[dom_struct]
 pub struct ServiceWorkerContainer {
     eventtarget: EventTarget,
-    controller: MutNullableJS<ServiceWorker>,
+    controller: MutNullableDom<ServiceWorker>,
     client: Dom<Client>
 }
 
diff --git a/components/script/dom/servoparser/mod.rs b/components/script/dom/servoparser/mod.rs
index 92d3b8a894e..0da5d9391d7 100644
--- a/components/script/dom/servoparser/mod.rs
+++ b/components/script/dom/servoparser/mod.rs
@@ -12,7 +12,7 @@ use dom::bindings::codegen::Bindings::ServoParserBinding;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::{Reflector, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{Dom, MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::characterdata::CharacterData;
 use dom::comment::Comment;
@@ -748,7 +748,7 @@ pub struct Sink {
     base_url: ServoUrl,
     document: Dom<Document>,
     current_line: u64,
-    script: MutNullableJS<HTMLScriptElement>,
+    script: MutNullableDom<HTMLScriptElement>,
 }
 
 #[allow(unrooted_must_root)]  // FIXME: really?
diff --git a/components/script/dom/storageevent.rs b/components/script/dom/storageevent.rs
index 5fa2f5da9dc..f5f8bc5577f 100644
--- a/components/script/dom/storageevent.rs
+++ b/components/script/dom/storageevent.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::StorageEventBinding::StorageEventMethods;
 use dom::bindings::error::Fallible;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::reflect_dom_object;
-use dom::bindings::root::{MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::event::{Event, EventBubbles, EventCancelable};
 use dom::storage::Storage;
@@ -23,7 +23,7 @@ pub struct StorageEvent {
     old_value: Option<DOMString>,
     new_value: Option<DOMString>,
     url: DOMString,
-    storage_area: MutNullableJS<Storage>
+    storage_area: MutNullableDom<Storage>
 }
 
 
@@ -39,7 +39,7 @@ impl StorageEvent {
             old_value: old_value,
             new_value: new_value,
             url: url,
-            storage_area: MutNullableJS::new(storage_area)
+            storage_area: MutNullableDom::new(storage_area)
         }
     }
 
diff --git a/components/script/dom/uievent.rs b/components/script/dom/uievent.rs
index 2c17f4961f2..d799b979245 100644
--- a/components/script/dom/uievent.rs
+++ b/components/script/dom/uievent.rs
@@ -8,7 +8,7 @@ use dom::bindings::codegen::Bindings::UIEventBinding::UIEventMethods;
 use dom::bindings::error::Fallible;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::reflect_dom_object;
-use dom::bindings::root::{MutNullableJS, Root, RootedReference};
+use dom::bindings::root::{MutNullableDom, Root, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::event::{Event, EventBubbles, EventCancelable};
 use dom::window::Window;
@@ -21,7 +21,7 @@ use std::default::Default;
 #[dom_struct]
 pub struct UIEvent {
     event: Event,
-    view: MutNullableJS<Window>,
+    view: MutNullableDom<Window>,
     detail: Cell<i32>
 }
 
diff --git a/components/script/dom/url.rs b/components/script/dom/url.rs
index b4d17fdc9b6..b19d2337142 100644
--- a/components/script/dom/url.rs
+++ b/components/script/dom/url.rs
@@ -6,7 +6,7 @@ use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::URLBinding::{self, URLMethods};
 use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::{DOMString, USVString};
 use dom::blob::Blob;
 use dom::globalscope::GlobalScope;
@@ -30,7 +30,7 @@ pub struct URL {
     url: DOMRefCell<ServoUrl>,
 
     // https://url.spec.whatwg.org/#dom-url-searchparams
-    search_params: MutNullableJS<URLSearchParams>,
+    search_params: MutNullableDom<URLSearchParams>,
 }
 
 impl URL {
diff --git a/components/script/dom/vrdisplay.rs b/components/script/dom/vrdisplay.rs
index d6e8d480c3d..c05ff88b19a 100644
--- a/components/script/dom/vrdisplay.rs
+++ b/components/script/dom/vrdisplay.rs
@@ -18,7 +18,7 @@ use dom::bindings::inheritance::Castable;
 use dom::bindings::num::Finite;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{MutDom, MutNullableJS, Root};
+use dom::bindings::root::{MutDom, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::event::Event;
 use dom::eventtarget::EventTarget;
@@ -54,12 +54,12 @@ pub struct VRDisplay {
     left_eye_params: MutDom<VREyeParameters>,
     right_eye_params: MutDom<VREyeParameters>,
     capabilities: MutDom<VRDisplayCapabilities>,
-    stage_params: MutNullableJS<VRStageParameters>,
+    stage_params: MutNullableDom<VRStageParameters>,
     #[ignore_heap_size_of = "Defined in rust-webvr"]
     frame_data: DOMRefCell<WebVRFrameData>,
     #[ignore_heap_size_of = "Defined in rust-webvr"]
     layer: DOMRefCell<WebVRLayer>,
-    layer_ctx: MutNullableJS<WebGLRenderingContext>,
+    layer_ctx: MutNullableDom<WebGLRenderingContext>,
     #[ignore_heap_size_of = "Defined in rust-webvr"]
     next_raf_id: Cell<u32>,
     /// List of request animation frame callbacks
@@ -103,10 +103,10 @@ impl VRDisplay {
             left_eye_params: MutDom::new(&*VREyeParameters::new(display.left_eye_parameters.clone(), &global)),
             right_eye_params: MutDom::new(&*VREyeParameters::new(display.right_eye_parameters.clone(), &global)),
             capabilities: MutDom::new(&*VRDisplayCapabilities::new(display.capabilities.clone(), &global)),
-            stage_params: MutNullableJS::new(stage.as_ref().map(|v| v.deref())),
+            stage_params: MutNullableDom::new(stage.as_ref().map(|v| v.deref())),
             frame_data: DOMRefCell::new(Default::default()),
             layer: DOMRefCell::new(Default::default()),
-            layer_ctx: MutNullableJS::default(),
+            layer_ctx: MutNullableDom::default(),
             next_raf_id: Cell::new(1),
             raf_callback_list: DOMRefCell::new(vec![]),
             frame_data_status: Cell::new(VRFrameDataStatus::Waiting),
diff --git a/components/script/dom/webgl_extensions/ext/oesvertexarrayobject.rs b/components/script/dom/webgl_extensions/ext/oesvertexarrayobject.rs
index f7414bcbb1b..00c9d1abdda 100644
--- a/components/script/dom/webgl_extensions/ext/oesvertexarrayobject.rs
+++ b/components/script/dom/webgl_extensions/ext/oesvertexarrayobject.rs
@@ -6,7 +6,7 @@ use canvas_traits::webgl::{webgl_channel, WebGLCommand, WebGLError};
 use dom::bindings::codegen::Bindings::OESVertexArrayObjectBinding::{self, OESVertexArrayObjectMethods};
 use dom::bindings::codegen::Bindings::OESVertexArrayObjectBinding::OESVertexArrayObjectConstants;
 use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::webglrenderingcontext::WebGLRenderingContext;
 use dom::webglvertexarrayobjectoes::WebGLVertexArrayObjectOES;
 use dom_struct::dom_struct;
@@ -20,7 +20,7 @@ use super::{WebGLExtension, WebGLExtensions};
 pub struct OESVertexArrayObject {
     reflector_: Reflector,
     ctx: Dom<WebGLRenderingContext>,
-    bound_vao: MutNullableJS<WebGLVertexArrayObjectOES>,
+    bound_vao: MutNullableDom<WebGLVertexArrayObjectOES>,
 }
 
 impl OESVertexArrayObject {
@@ -28,7 +28,7 @@ impl OESVertexArrayObject {
         Self {
             reflector_: Reflector::new(),
             ctx: Dom::from_ref(ctx),
-            bound_vao: MutNullableJS::new(None)
+            bound_vao: MutNullableDom::new(None)
         }
     }
 
diff --git a/components/script/dom/webgl_extensions/ext/webglvertexarrayobjectoes.rs b/components/script/dom/webgl_extensions/ext/webglvertexarrayobjectoes.rs
index ccd103e07a2..3ef5f8bbefa 100644
--- a/components/script/dom/webgl_extensions/ext/webglvertexarrayobjectoes.rs
+++ b/components/script/dom/webgl_extensions/ext/webglvertexarrayobjectoes.rs
@@ -8,7 +8,7 @@ use core::iter::FromIterator;
 use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::WebGLVertexArrayObjectOESBinding;
 use dom::bindings::reflector::reflect_dom_object;
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::globalscope::GlobalScope;
 use dom::webglbuffer::WebGLBuffer;
 use dom::webglobject::WebGLObject;
@@ -23,7 +23,7 @@ pub struct WebGLVertexArrayObjectOES {
     ever_bound: Cell<bool>,
     is_deleted: Cell<bool>,
     bound_attrib_buffers: DOMRefCell<HashMap<u32, Dom<WebGLBuffer>>>,
-    bound_buffer_element_array: MutNullableJS<WebGLBuffer>,
+    bound_buffer_element_array: MutNullableDom<WebGLBuffer>,
 }
 
 impl WebGLVertexArrayObjectOES {
@@ -34,7 +34,7 @@ impl WebGLVertexArrayObjectOES {
             ever_bound: Cell::new(false),
             is_deleted: Cell::new(false),
             bound_attrib_buffers: DOMRefCell::new(HashMap::new()),
-            bound_buffer_element_array: MutNullableJS::new(None),
+            bound_buffer_element_array: MutNullableDom::new(None),
         }
     }
 
diff --git a/components/script/dom/webgl_extensions/wrapper.rs b/components/script/dom/webgl_extensions/wrapper.rs
index 53aba5ed462..fa4d1112a3c 100644
--- a/components/script/dom/webgl_extensions/wrapper.rs
+++ b/components/script/dom/webgl_extensions/wrapper.rs
@@ -4,7 +4,7 @@
 
 use core::nonzero::NonZero;
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::trace::JSTraceable;
 use dom::webglrenderingcontext::WebGLRenderingContext;
 use heapsize::HeapSizeOf;
@@ -29,15 +29,15 @@ pub trait WebGLExtensionWrapper: JSTraceable + HeapSizeOf {
 #[must_root]
 #[derive(HeapSizeOf, JSTraceable)]
 pub struct TypedWebGLExtensionWrapper<T: WebGLExtension> {
-    extension: MutNullableJS<T::Extension>
+    extension: MutNullableDom<T::Extension>
 }
 
 /// Typed WebGL Extension implementation.
-/// Exposes the exact MutNullableJS<DOMObject> type defined by the extension.
+/// Exposes the exact MutNullableDom<DOMObject> type defined by the extension.
 impl<T: WebGLExtension> TypedWebGLExtensionWrapper<T> {
     pub fn new() -> TypedWebGLExtensionWrapper<T> {
         TypedWebGLExtensionWrapper {
-            extension: MutNullableJS::new(None)
+            extension: MutNullableDom::new(None)
         }
     }
 }
diff --git a/components/script/dom/webglprogram.rs b/components/script/dom/webglprogram.rs
index cc242503607..39262c2f5bd 100644
--- a/components/script/dom/webglprogram.rs
+++ b/components/script/dom/webglprogram.rs
@@ -8,7 +8,7 @@ use canvas_traits::webgl::webgl_channel;
 use dom::bindings::codegen::Bindings::WebGLProgramBinding;
 use dom::bindings::codegen::Bindings::WebGLRenderingContextBinding::WebGLRenderingContextConstants as constants;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::webglactiveinfo::WebGLActiveInfo;
 use dom::webglobject::WebGLObject;
@@ -25,8 +25,8 @@ pub struct WebGLProgram {
     is_deleted: Cell<bool>,
     link_called: Cell<bool>,
     linked: Cell<bool>,
-    fragment_shader: MutNullableJS<WebGLShader>,
-    vertex_shader: MutNullableJS<WebGLShader>,
+    fragment_shader: MutNullableDom<WebGLShader>,
+    vertex_shader: MutNullableDom<WebGLShader>,
     #[ignore_heap_size_of = "Defined in ipc-channel"]
     renderer: WebGLMsgSender,
 }
diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index 64148a0a435..9f3b9f286e8 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -20,7 +20,7 @@ use dom::bindings::conversions::{ConversionResult, FromJSValConvertible, ToJSVal
 use dom::bindings::error::{Error, Fallible};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
-use dom::bindings::root::{Dom, LayoutJS, MutNullableJS, Root};
+use dom::bindings::root::{Dom, LayoutJS, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::event::{Event, EventBubbles, EventCancelable};
 use dom::htmlcanvaselement::HTMLCanvasElement;
@@ -145,14 +145,14 @@ pub struct WebGLRenderingContext {
     last_error: Cell<Option<WebGLError>>,
     texture_unpacking_settings: Cell<TextureUnpacking>,
     texture_unpacking_alignment: Cell<u32>,
-    bound_framebuffer: MutNullableJS<WebGLFramebuffer>,
-    bound_renderbuffer: MutNullableJS<WebGLRenderbuffer>,
-    bound_texture_2d: MutNullableJS<WebGLTexture>,
-    bound_texture_cube_map: MutNullableJS<WebGLTexture>,
-    bound_buffer_array: MutNullableJS<WebGLBuffer>,
-    bound_buffer_element_array: MutNullableJS<WebGLBuffer>,
+    bound_framebuffer: MutNullableDom<WebGLFramebuffer>,
+    bound_renderbuffer: MutNullableDom<WebGLRenderbuffer>,
+    bound_texture_2d: MutNullableDom<WebGLTexture>,
+    bound_texture_cube_map: MutNullableDom<WebGLTexture>,
+    bound_buffer_array: MutNullableDom<WebGLBuffer>,
+    bound_buffer_element_array: MutNullableDom<WebGLBuffer>,
     bound_attrib_buffers: DOMRefCell<FnvHashMap<u32, Dom<WebGLBuffer>>>,
-    current_program: MutNullableJS<WebGLProgram>,
+    current_program: MutNullableDom<WebGLProgram>,
     #[ignore_heap_size_of = "Because it's small"]
     current_vertex_attrib_0: Cell<(f32, f32, f32, f32)>,
     #[ignore_heap_size_of = "Because it's small"]
@@ -189,14 +189,14 @@ impl WebGLRenderingContext {
                 last_error: Cell::new(None),
                 texture_unpacking_settings: Cell::new(CONVERT_COLORSPACE),
                 texture_unpacking_alignment: Cell::new(4),
-                bound_framebuffer: MutNullableJS::new(None),
-                bound_texture_2d: MutNullableJS::new(None),
-                bound_texture_cube_map: MutNullableJS::new(None),
-                bound_buffer_array: MutNullableJS::new(None),
-                bound_buffer_element_array: MutNullableJS::new(None),
+                bound_framebuffer: MutNullableDom::new(None),
+                bound_texture_2d: MutNullableDom::new(None),
+                bound_texture_cube_map: MutNullableDom::new(None),
+                bound_buffer_array: MutNullableDom::new(None),
+                bound_buffer_element_array: MutNullableDom::new(None),
                 bound_attrib_buffers: DOMRefCell::new(Default::default()),
-                bound_renderbuffer: MutNullableJS::new(None),
-                current_program: MutNullableJS::new(None),
+                bound_renderbuffer: MutNullableDom::new(None),
+                current_program: MutNullableDom::new(None),
                 current_vertex_attrib_0: Cell::new((0f32, 0f32, 0f32, 1f32)),
                 current_scissor: Cell::new((0, 0, size.width, size.height)),
                 current_clear_color: Cell::new((0.0, 0.0, 0.0, 0.0)),
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index b80beb186d0..1cb9bd37158 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -21,7 +21,7 @@ use dom::bindings::inheritance::Castable;
 use dom::bindings::num::Finite;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::bindings::structuredclone::StructuredCloneData;
 use dom::bindings::trace::RootedTraceableBox;
@@ -176,22 +176,22 @@ pub struct Window {
     file_reading_task_source: FileReadingTaskSource,
     #[ignore_heap_size_of = "task sources are hard"]
     performance_timeline_task_source: PerformanceTimelineTaskSource,
-    navigator: MutNullableJS<Navigator>,
+    navigator: MutNullableDom<Navigator>,
     #[ignore_heap_size_of = "Arc"]
     image_cache: Arc<ImageCache>,
     #[ignore_heap_size_of = "channels are hard"]
     image_cache_chan: Sender<ImageCacheMsg>,
-    window_proxy: MutNullableJS<WindowProxy>,
-    document: MutNullableJS<Document>,
-    location: MutNullableJS<Location>,
-    history: MutNullableJS<History>,
-    custom_element_registry: MutNullableJS<CustomElementRegistry>,
-    performance: MutNullableJS<Performance>,
+    window_proxy: MutNullableDom<WindowProxy>,
+    document: MutNullableDom<Document>,
+    location: MutNullableDom<Location>,
+    history: MutNullableDom<History>,
+    custom_element_registry: MutNullableDom<CustomElementRegistry>,
+    performance: MutNullableDom<Performance>,
     navigation_start: Cell<u64>,
     navigation_start_precise: Cell<f64>,
-    screen: MutNullableJS<Screen>,
-    session_storage: MutNullableJS<Storage>,
-    local_storage: MutNullableJS<Storage>,
+    screen: MutNullableDom<Screen>,
+    session_storage: MutNullableDom<Storage>,
+    local_storage: MutNullableDom<Storage>,
     status: DOMRefCell<DOMString>,
 
     /// For sending timeline markers. Will be ignored if
@@ -263,7 +263,7 @@ pub struct Window {
     /// All the MediaQueryLists we need to update
     media_query_lists: WeakMediaQueryListVec,
 
-    test_runner: MutNullableJS<TestRunner>,
+    test_runner: MutNullableDom<TestRunner>,
 
     /// A handle for communicating messages to the webvr thread, if available.
     #[ignore_heap_size_of = "channels are hard"]
@@ -287,9 +287,9 @@ pub struct Window {
     unminified_js_dir: DOMRefCell<Option<String>>,
 
     /// Worklets
-    test_worklet: MutNullableJS<Worklet>,
+    test_worklet: MutNullableDom<Worklet>,
     /// https://drafts.css-houdini.org/css-paint-api-1/#paint-worklet
-    paint_worklet: MutNullableJS<Worklet>,
+    paint_worklet: MutNullableDom<Worklet>,
 }
 
 impl Window {
diff --git a/components/script/dom/workerglobalscope.rs b/components/script/dom/workerglobalscope.rs
index 6817a466400..252be0f3bf1 100644
--- a/components/script/dom/workerglobalscope.rs
+++ b/components/script/dom/workerglobalscope.rs
@@ -10,7 +10,7 @@ use dom::bindings::codegen::UnionTypes::RequestOrUSVString;
 use dom::bindings::error::{Error, ErrorResult, Fallible, report_pending_exception};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::settings_stack::AutoEntryScript;
 use dom::bindings::str::DOMString;
 use dom::bindings::trace::RootedTraceableBox;
@@ -77,8 +77,8 @@ pub struct WorkerGlobalScope {
     closing: Option<Arc<AtomicBool>>,
     #[ignore_heap_size_of = "Defined in js"]
     runtime: Runtime,
-    location: MutNullableJS<WorkerLocation>,
-    navigator: MutNullableJS<WorkerNavigator>,
+    location: MutNullableDom<WorkerLocation>,
+    navigator: MutNullableDom<WorkerNavigator>,
 
     #[ignore_heap_size_of = "Defined in ipc-channel"]
     /// Optional `IpcSender` for sending the `DevtoolScriptControlMsg`
@@ -91,7 +91,7 @@ pub struct WorkerGlobalScope {
     from_devtools_receiver: Receiver<DevtoolScriptControlMsg>,
 
     navigation_start_precise: f64,
-    performance: MutNullableJS<Performance>,
+    performance: MutNullableDom<Performance>,
 }
 
 impl WorkerGlobalScope {
diff --git a/components/script/dom/workernavigator.rs b/components/script/dom/workernavigator.rs
index 165deaf5b5d..d2d99be1264 100644
--- a/components/script/dom/workernavigator.rs
+++ b/components/script/dom/workernavigator.rs
@@ -5,7 +5,7 @@
 use dom::bindings::codegen::Bindings::WorkerNavigatorBinding;
 use dom::bindings::codegen::Bindings::WorkerNavigatorBinding::WorkerNavigatorMethods;
 use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
-use dom::bindings::root::{MutNullableJS, Root};
+use dom::bindings::root::{MutNullableDom, Root};
 use dom::bindings::str::DOMString;
 use dom::navigatorinfo;
 use dom::permissions::Permissions;
@@ -16,7 +16,7 @@ use dom_struct::dom_struct;
 #[dom_struct]
 pub struct WorkerNavigator {
     reflector_: Reflector,
-    permissions: MutNullableJS<Permissions>,
+    permissions: MutNullableDom<Permissions>,
 }
 
 impl WorkerNavigator {
diff --git a/components/script/dom/xmlhttprequest.rs b/components/script/dom/xmlhttprequest.rs
index a4446d55a56..a08982c4255 100644
--- a/components/script/dom/xmlhttprequest.rs
+++ b/components/script/dom/xmlhttprequest.rs
@@ -16,7 +16,7 @@ use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
-use dom::bindings::root::{Dom, MutNullableJS, Root};
+use dom::bindings::root::{Dom, MutNullableDom, Root};
 use dom::bindings::str::{ByteString, DOMString, USVString, is_token};
 use dom::blob::{Blob, BlobImpl};
 use dom::document::{Document, HasBrowsingContext, IsHTMLDocument};
@@ -129,8 +129,8 @@ pub struct XMLHttpRequest {
     status_text: DOMRefCell<ByteString>,
     response: DOMRefCell<ByteString>,
     response_type: Cell<XMLHttpRequestResponseType>,
-    response_xml: MutNullableJS<Document>,
-    response_blob: MutNullableJS<Blob>,
+    response_xml: MutNullableDom<Document>,
+    response_blob: MutNullableDom<Blob>,
     #[ignore_heap_size_of = "Defined in rust-mozjs"]
     response_json: Heap<JSVal>,
     #[ignore_heap_size_of = "Defined in hyper"]
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 92b8aa4b9d5..6da18b8f28b 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -34,7 +34,7 @@ use dom::bindings::conversions::{ConversionResult, FromJSValConvertible, Stringi
 use dom::bindings::inheritance::Castable;
 use dom::bindings::num::Finite;
 use dom::bindings::reflector::DomObject;
-use dom::bindings::root::{Dom, MutNullableJS, Root, RootCollection};
+use dom::bindings::root::{Dom, MutNullableDom, Root, RootCollection};
 use dom::bindings::root::{RootCollectionPtr, RootedReference};
 use dom::bindings::str::DOMString;
 use dom::bindings::structuredclone::StructuredCloneData;
@@ -458,7 +458,7 @@ pub struct ScriptThread {
     js_runtime: Rc<Runtime>,
 
     /// The topmost element over the mouse.
-    topmost_mouse_over_target: MutNullableJS<Element>,
+    topmost_mouse_over_target: MutNullableDom<Element>,
 
     /// List of pipelines that have been owned and closed by this script thread.
     closed_pipelines: DOMRefCell<HashSet<PipelineId>>,
@@ -846,7 +846,7 @@ impl ScriptThread {
             devtools_sender: ipc_devtools_sender,
 
             js_runtime: Rc::new(runtime),
-            topmost_mouse_over_target: MutNullableJS::new(Default::default()),
+            topmost_mouse_over_target: MutNullableDom::new(Default::default()),
             closed_pipelines: DOMRefCell::new(HashSet::new()),
 
             scheduler_chan: state.scheduler_chan,