Auto merge of #8060 - nox:deref-js, r=Ms2ger

Implement Deref<Target=T> for JS<T> where T: Reflectable

We can only borrow `JS<T>` from rooted things, so it's safe to deref it.
The only types that provide mutable `JS<T>` things are `MutHeap<JS<T>>` and
`MutNullableHeap<JS<T>>`, which don't actually expose that they contain
`JS<T>` values.

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23 files changed, 187 insertions, 274 deletions

diff --git a/components/script/dom/bindings/js.rs b/components/script/dom/bindings/js.rs
index aea80d88431..1ef1d93a86d 100644
--- a/components/script/dom/bindings/js.rs
+++ b/components/script/dom/bindings/js.rs
@@ -96,6 +96,16 @@ impl<T: Reflectable> JS<T> {
     }
 }
 
+impl<T: Reflectable> Deref for JS<T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        // We can only have &JS<T> from a rooted thing, so it's safe to deref
+        // it to &T.
+        unsafe { &**self.ptr }
+    }
+}
+
 impl<T: Reflectable> JSTraceable for JS<T> {
     fn trace(&self, trc: *mut JSTracer) {
         trace_reflector(trc, "", unsafe { (**self.ptr).reflector() });
diff --git a/components/script/dom/browsercontext.rs b/components/script/dom/browsercontext.rs
index af2bfbdc81e..60dbdc5523e 100644
--- a/components/script/dom/browsercontext.rs
+++ b/components/script/dom/browsercontext.rs
@@ -44,17 +44,16 @@ impl BrowsingContext {
         }
     }
 
-    pub fn active_document(&self) -> Root<Document> {
-        self.history[self.active_index].document.root()
+    pub fn active_document(&self) -> &Document {
+        &*self.history[self.active_index].document
     }
 
-    pub fn active_window(&self) -> Root<Window> {
-        let doc = self.active_document();
-        doc.r().window()
+    pub fn active_window(&self) -> &Window {
+        self.active_document().window()
     }
 
-    pub fn frame_element(&self) -> Option<Root<Element>> {
-        self.frame_element.as_ref().map(JS::root)
+    pub fn frame_element(&self) -> Option<&Element> {
+        self.frame_element.as_ref().map(|element| &**element)
     }
 
     pub fn window_proxy(&self) -> *mut JSObject {
@@ -64,8 +63,8 @@ impl BrowsingContext {
 
     #[allow(unsafe_code)]
     pub fn create_window_proxy(&mut self) {
-        let win = self.active_window();
-        let win = win.r();
+        // We inline self.active_window() because we can't borrow *self here.
+        let win = self.history[self.active_index].document.window();
 
         let WindowProxyHandler(handler) = win.windowproxy_handler();
         assert!(!handler.is_null());
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 7ce96fe9424..8fe2fee79c5 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -232,8 +232,8 @@ impl Document {
     }
 
     #[inline]
-    pub fn window(&self) -> Root<Window> {
-        self.window.root()
+    pub fn window(&self) -> &Window {
+        &*self.window
     }
 
     #[inline]
@@ -248,13 +248,11 @@ impl Document {
 
     // https://html.spec.whatwg.org/multipage/#fully-active
     pub fn is_fully_active(&self) -> bool {
-        let window = self.window.root();
-        let window = window.r();
-        let browsing_context = window.browsing_context();
+        let browsing_context = self.window.browsing_context();
         let browsing_context = browsing_context.as_ref().unwrap();
         let active_document = browsing_context.active_document();
 
-        if self != active_document.r() {
+        if self != active_document {
             return false;
         }
         // FIXME: It should also check whether the browser context is top-level or not
@@ -308,9 +306,7 @@ impl Document {
         self.quirks_mode.set(mode);
 
         if mode == Quirks {
-            let window = self.window.root();
-            let window = window.r();
-            let LayoutChan(ref layout_chan) = window.layout_chan();
+            let LayoutChan(ref layout_chan) = self.window.layout_chan();
             layout_chan.send(Msg::SetQuirksMode).unwrap();
         }
     }
@@ -336,10 +332,9 @@ impl Document {
             }
 
             self.reflow_timeout.set(None);
-            let window = self.window.root();
-            window.r().reflow(ReflowGoal::ForDisplay,
-                              ReflowQueryType::NoQuery,
-                              ReflowReason::RefreshTick);
+            self.window.reflow(ReflowGoal::ForDisplay,
+                               ReflowQueryType::NoQuery,
+                               ReflowReason::RefreshTick);
         }
     }
 
@@ -449,8 +444,7 @@ impl Document {
             None => return None,
         };
         let root = NodeCast::from_ref(root);
-        let win = self.window.root();
-        let address = match win.r().layout().hit_test(root.to_trusted_node_address(), *point) {
+        let address = match self.window.layout().hit_test(root.to_trusted_node_address(), *point) {
             Ok(HitTestResponse(node_address)) => Some(node_address),
             Err(()) => {
                 debug!("layout query error");
@@ -467,8 +461,7 @@ impl Document {
             None => return vec!(),
         };
         let root = NodeCast::from_ref(root);
-        let win = self.window.root();
-        match win.r().layout().mouse_over(root.to_trusted_node_address(), *point) {
+        match self.window.layout().mouse_over(root.to_trusted_node_address(), *point) {
             Ok(MouseOverResponse(node_address)) => node_address,
             Err(()) => vec!(),
         }
@@ -478,8 +471,7 @@ impl Document {
     pub fn set_ready_state(&self, state: DocumentReadyState) {
         self.ready_state.set(state);
 
-        let window = self.window.root();
-        let event = Event::new(GlobalRef::Window(window.r()), "readystatechange".to_owned(),
+        let event = Event::new(GlobalRef::Window(&self.window), "readystatechange".to_owned(),
                                EventBubbles::DoesNotBubble,
                                EventCancelable::NotCancelable);
         let target = EventTargetCast::from_ref(self);
@@ -527,9 +519,8 @@ impl Document {
             // Update the focus state for all elements in the focus chain.
             // https://html.spec.whatwg.org/multipage/#focus-chain
             if focus_type == FocusType::Element {
-                let window = self.window.root();
-                let ConstellationChan(ref chan) = window.r().constellation_chan();
-                let event = ConstellationMsg::Focus(window.r().pipeline());
+                let ConstellationChan(ref chan) = self.window.constellation_chan();
+                let event = ConstellationMsg::Focus(self.window.pipeline());
                 chan.send(event).unwrap();
             }
         }
@@ -546,8 +537,6 @@ impl Document {
     /// Sends this document's title to the compositor.
     pub fn send_title_to_compositor(&self) {
         let window = self.window();
-        // FIXME(https://github.com/rust-lang/rust/issues/23338)
-        let window = window.r();
         let compositor = window.compositor();
         compositor.send(ScriptToCompositorMsg::SetTitle(window.pipeline(), Some(self.Title()))).unwrap();
     }
@@ -598,17 +587,15 @@ impl Document {
             self.begin_focus_transaction();
         }
 
-        let window = self.window.root();
-
         // https://dvcs.w3.org/hg/dom3events/raw-file/tip/html/DOM3-Events.html#event-type-click
         let x = point.x as i32;
         let y = point.y as i32;
         let clickCount = 1;
-        let event = MouseEvent::new(window.r(),
+        let event = MouseEvent::new(&self.window,
                                     mouse_event_type_string,
                                     EventBubbles::Bubbles,
                                     EventCancelable::Cancelable,
-                                    Some(window.r()),
+                                    Some(&self.window),
                                     clickCount,
                                     x, y, x, y,
                                     false, false, false, false,
@@ -630,7 +617,9 @@ impl Document {
         if let MouseEventType::Click = mouse_event_type {
             self.commit_focus_transaction(FocusType::Element);
         }
-        window.r().reflow(ReflowGoal::ForDisplay, ReflowQueryType::NoQuery, ReflowReason::MouseEvent);
+        self.window.reflow(ReflowGoal::ForDisplay,
+                           ReflowQueryType::NoQuery,
+                           ReflowReason::MouseEvent);
     }
 
     pub fn fire_mouse_event(&self,
@@ -640,13 +629,11 @@ impl Document {
         let x = point.x.to_i32().unwrap_or(0);
         let y = point.y.to_i32().unwrap_or(0);
 
-        let window = self.window.root();
-
-        let mouse_event = MouseEvent::new(window.r(),
+        let mouse_event = MouseEvent::new(&self.window,
                                           event_name,
                                           EventBubbles::Bubbles,
                                           EventCancelable::Cancelable,
-                                          Some(window.r()),
+                                          Some(&self.window),
                                           0i32,
                                           x, y, x, y,
                                           false, false, false, false,
@@ -714,10 +701,9 @@ impl Document {
         prev_mouse_over_targets.clear();
         prev_mouse_over_targets.append(&mut *mouse_over_targets);
 
-        let window = self.window.root();
-        window.r().reflow(ReflowGoal::ForDisplay,
-                          ReflowQueryType::NoQuery,
-                          ReflowReason::MouseEvent);
+        self.window.reflow(ReflowGoal::ForDisplay,
+                           ReflowQueryType::NoQuery,
+                           ReflowReason::MouseEvent);
     }
 
     /// The entry point for all key processing for web content
@@ -726,14 +712,13 @@ impl Document {
                           state: KeyState,
                           modifiers: KeyModifiers,
                           compositor: &mut IpcSender<ScriptToCompositorMsg>) {
-        let window = self.window.root();
         let focused = self.get_focused_element();
         let body = self.GetBody();
 
         let target = match (&focused, &body) {
             (&Some(ref focused), _) => EventTargetCast::from_ref(focused.r()),
             (&None, &Some(ref body)) => EventTargetCast::from_ref(body.r()),
-            (&None, &None) => EventTargetCast::from_ref(window.r()),
+            (&None, &None) => EventTargetCast::from_ref(&*self.window),
         };
 
         let ctrl = modifiers.contains(CONTROL);
@@ -750,8 +735,8 @@ impl Document {
 
         let props = KeyboardEvent::key_properties(key, modifiers);
 
-        let keyevent = KeyboardEvent::new(window.r(), ev_type, true, true,
-                                          Some(window.r()), 0, Some(key),
+        let keyevent = KeyboardEvent::new(&self.window, ev_type, true, true,
+                                          Some(&self.window), 0, Some(key),
                                           props.key_string.to_owned(), props.code.to_owned(),
                                           props.location, is_repeating, is_composing,
                                           ctrl, alt, shift, meta,
@@ -763,8 +748,8 @@ impl Document {
         // https://dvcs.w3.org/hg/dom3events/raw-file/tip/html/DOM3-Events.html#keys-cancelable-keys
         if state != KeyState::Released && props.is_printable() && !prevented {
             // https://dvcs.w3.org/hg/dom3events/raw-file/tip/html/DOM3-Events.html#keypress-event-order
-            let event = KeyboardEvent::new(window.r(), "keypress".to_owned(),
-                                           true, true, Some(window.r()), 0, Some(key),
+            let event = KeyboardEvent::new(&self.window, "keypress".to_owned(),
+                                           true, true, Some(&self.window), 0, Some(key),
                                             props.key_string.to_owned(), props.code.to_owned(),
                                            props.location, is_repeating, is_composing,
                                            ctrl, alt, shift, meta,
@@ -804,7 +789,9 @@ impl Document {
             _ => ()
         }
 
-        window.r().reflow(ReflowGoal::ForDisplay, ReflowQueryType::NoQuery, ReflowReason::KeyEvent);
+        self.window.reflow(ReflowGoal::ForDisplay,
+                           ReflowQueryType::NoQuery,
+                           ReflowReason::KeyEvent);
     }
 
     pub fn node_from_nodes_and_strings(&self, nodes: Vec<NodeOrString>)
@@ -856,10 +843,8 @@ impl Document {
 
     pub fn trigger_mozbrowser_event(&self, event: MozBrowserEvent) {
         if htmliframeelement::mozbrowser_enabled() {
-            let window = self.window.root();
-
-            if let Some((containing_pipeline_id, subpage_id)) = window.r().parent_info() {
-                let ConstellationChan(ref chan) = window.r().constellation_chan();
+            if let Some((containing_pipeline_id, subpage_id)) = self.window.parent_info() {
+                let ConstellationChan(ref chan) = self.window.constellation_chan();
                 let event = ConstellationMsg::MozBrowserEvent(containing_pipeline_id,
                                                               subpage_id,
                                                               event);
@@ -870,16 +855,14 @@ impl Document {
 
     /// https://html.spec.whatwg.org/multipage/#dom-window-requestanimationframe
     pub fn request_animation_frame(&self, callback: Box<FnBox(f64)>) -> u32 {
-        let window = self.window.root();
-        let window = window.r();
         let ident = self.animation_frame_ident.get() + 1;
 
         self.animation_frame_ident.set(ident);
         self.animation_frame_list.borrow_mut().insert(ident, callback);
 
         // TODO: Should tick animation only when document is visible
-        let ConstellationChan(ref chan) = window.constellation_chan();
-        let event = ConstellationMsg::ChangeRunningAnimationsState(window.pipeline(),
+        let ConstellationChan(ref chan) = self.window.constellation_chan();
+        let event = ConstellationMsg::ChangeRunningAnimationsState(self.window.pipeline(),
                                                                    AnimationState::AnimationCallbacksPresent);
         chan.send(event).unwrap();
 
@@ -890,10 +873,8 @@ impl Document {
     pub fn cancel_animation_frame(&self, ident: u32) {
         self.animation_frame_list.borrow_mut().remove(&ident);
         if self.animation_frame_list.borrow().is_empty() {
-            let window = self.window.root();
-            let window = window.r();
-            let ConstellationChan(ref chan) = window.constellation_chan();
-            let event = ConstellationMsg::ChangeRunningAnimationsState(window.pipeline(),
+            let ConstellationChan(ref chan) = self.window.constellation_chan();
+            let event = ConstellationMsg::ChangeRunningAnimationsState(self.window.pipeline(),
                                                                        AnimationState::NoAnimationCallbacksPresent);
             chan.send(event).unwrap();
         }
@@ -906,16 +887,12 @@ impl Document {
             let mut list = self.animation_frame_list.borrow_mut();
             animation_frame_list = Vec::from_iter(list.drain());
 
-            let window = self.window.root();
-            let window = window.r();
-            let ConstellationChan(ref chan) = window.constellation_chan();
-            let event = ConstellationMsg::ChangeRunningAnimationsState(window.pipeline(),
+            let ConstellationChan(ref chan) = self.window.constellation_chan();
+            let event = ConstellationMsg::ChangeRunningAnimationsState(self.window.pipeline(),
                                                                        AnimationState::NoAnimationCallbacksPresent);
             chan.send(event).unwrap();
         }
-        let window = self.window.root();
-        let window = window.r();
-        let performance = window.Performance();
+        let performance = self.window.Performance();
         let performance = performance.r();
         let timing = performance.Now();
 
@@ -923,9 +900,9 @@ impl Document {
             callback(*timing);
         }
 
-        window.reflow(ReflowGoal::ForDisplay,
-                      ReflowQueryType::NoQuery,
-                      ReflowReason::RequestAnimationFrame);
+       self.window.reflow(ReflowGoal::ForDisplay,
+                          ReflowQueryType::NoQuery,
+                          ReflowReason::RequestAnimationFrame);
     }
 
     pub fn prepare_async_load(&self, load: LoadType) -> PendingAsyncLoad {
@@ -949,9 +926,8 @@ impl Document {
     }
 
     pub fn notify_constellation_load(&self) {
-        let window = self.window.root();
-        let pipeline_id = window.r().pipeline();
-        let ConstellationChan(ref chan) = window.r().constellation_chan();
+        let pipeline_id = self.window.pipeline();
+        let ConstellationChan(ref chan) = self.window.constellation_chan();
         let event = ConstellationMsg::DOMLoad(pipeline_id);
         chan.send(event).unwrap();
 
@@ -1092,12 +1068,11 @@ impl Document {
     }
 
     fn create_node_list<F: Fn(&Node) -> bool>(&self, callback: F) -> Root<NodeList> {
-        let window = self.window.root();
         let doc = self.GetDocumentElement();
         let maybe_node = doc.r().map(NodeCast::from_ref);
         let iter = maybe_node.iter().flat_map(|node| node.traverse_preorder())
                              .filter(|node| callback(node.r()));
-        NodeList::new_simple_list(window.r(), iter)
+        NodeList::new_simple_list(&self.window, iter)
     }
 
     fn get_html_element(&self) -> Option<Root<HTMLHtmlElement>> {
@@ -1116,7 +1091,7 @@ impl Document {
                 IsHTMLDocument::NonHTMLDocument
             };
             let new_doc = Document::new(
-                &*self.window(), None, doctype, None, None,
+                self.window(), None, doctype, None, None,
                 DocumentSource::NotFromParser, DocumentLoader::new(&self.loader()));
             new_doc.appropriate_template_contents_owner_document.set(Some(&new_doc));
             new_doc
@@ -1168,9 +1143,7 @@ impl DocumentMethods for Document {
     // https://html.spec.whatwg.org/multipage/#dom-document-hasfocus
     fn HasFocus(&self) -> bool {
         let target = self;                                                        // Step 1.
-        let window = self.window.root();
-        let window = window.r();
-        let browsing_context = window.browsing_context();
+        let browsing_context = self.window.browsing_context();
         let browsing_context = browsing_context.as_ref();
 
         match browsing_context {
@@ -1230,22 +1203,18 @@ impl DocumentMethods for Document {
 
     // https://dom.spec.whatwg.org/#dom-document-getelementsbytagname
     fn GetElementsByTagName(&self, tag_name: DOMString) -> Root<HTMLCollection> {
-        let window = self.window.root();
-        HTMLCollection::by_tag_name(window.r(), NodeCast::from_ref(self), tag_name)
+        HTMLCollection::by_tag_name(&self.window, NodeCast::from_ref(self), tag_name)
     }
 
     // https://dom.spec.whatwg.org/#dom-document-getelementsbytagnamens
     fn GetElementsByTagNameNS(&self, maybe_ns: Option<DOMString>, tag_name: DOMString)
                               -> Root<HTMLCollection> {
-        let window = self.window.root();
-        HTMLCollection::by_tag_name_ns(window.r(), NodeCast::from_ref(self), tag_name, maybe_ns)
+        HTMLCollection::by_tag_name_ns(&self.window, NodeCast::from_ref(self), tag_name, maybe_ns)
     }
 
     // https://dom.spec.whatwg.org/#dom-document-getelementsbyclassname
     fn GetElementsByClassName(&self, classes: DOMString) -> Root<HTMLCollection> {
-        let window = self.window.root();
-
-        HTMLCollection::by_class_name(window.r(), NodeCast::from_ref(self), classes)
+        HTMLCollection::by_class_name(&self.window, NodeCast::from_ref(self), classes)
     }
 
     // https://dom.spec.whatwg.org/#dom-nonelementparentnode-getelementbyid
@@ -1284,13 +1253,12 @@ impl DocumentMethods for Document {
             return Err(Error::InvalidCharacter);
         }
 
-        let window = self.window.root();
         let name = Atom::from_slice(&local_name);
         // repetition used because string_cache::atom::Atom is non-copyable
         let l_name = Atom::from_slice(&local_name);
         let value = AttrValue::String("".to_owned());
 
-        Ok(Attr::new(window.r(), name, value, l_name, ns!(""), None, None))
+        Ok(Attr::new(&self.window, name, value, l_name, ns!(""), None, None))
     }
 
     // https://dom.spec.whatwg.org/#dom-document-createattributens
@@ -1298,10 +1266,9 @@ impl DocumentMethods for Document {
                          -> Fallible<Root<Attr>> {
         let (namespace, prefix, local_name) =
             try!(validate_and_extract(namespace, &qualified_name));
-        let window = self.window.root();
         let value = AttrValue::String("".to_owned());
         let qualified_name = Atom::from_slice(&qualified_name);
-        Ok(Attr::new(window.r(), local_name, value, qualified_name,
+        Ok(Attr::new(&self.window, local_name, value, qualified_name,
                      namespace, prefix, None))
     }
 
@@ -1369,22 +1336,20 @@ impl DocumentMethods for Document {
 
     // https://dom.spec.whatwg.org/#dom-document-createevent
     fn CreateEvent(&self, mut interface: DOMString) -> Fallible<Root<Event>> {
-        let window = self.window.root();
-
         interface.make_ascii_lowercase();
         match &*interface {
             "uievents" | "uievent" => Ok(EventCast::from_root(
-                UIEvent::new_uninitialized(window.r()))),
+                UIEvent::new_uninitialized(&self.window))),
             "mouseevents" | "mouseevent" => Ok(EventCast::from_root(
-                MouseEvent::new_uninitialized(window.r()))),
+                MouseEvent::new_uninitialized(&self.window))),
             "customevent" => Ok(EventCast::from_root(
-                CustomEvent::new_uninitialized(GlobalRef::Window(window.r())))),
+                CustomEvent::new_uninitialized(GlobalRef::Window(&self.window)))),
             "htmlevents" | "events" | "event" => Ok(Event::new_uninitialized(
-                GlobalRef::Window(window.r()))),
+                GlobalRef::Window(&self.window))),
             "keyboardevent" | "keyevents" => Ok(EventCast::from_root(
-                KeyboardEvent::new_uninitialized(window.r()))),
+                KeyboardEvent::new_uninitialized(&self.window))),
             "messageevent" => Ok(EventCast::from_root(
-                MessageEvent::new_uninitialized(GlobalRef::Window(window.r())))),
+                MessageEvent::new_uninitialized(GlobalRef::Window(&self.window)))),
             _ => Err(Error::NotSupported)
         }
     }
@@ -1585,20 +1550,18 @@ impl DocumentMethods for Document {
     // https://html.spec.whatwg.org/multipage/#dom-document-images
     fn Images(&self) -> Root<HTMLCollection> {
         self.images.or_init(|| {
-            let window = self.window.root();
             let root = NodeCast::from_ref(self);
             let filter = box ImagesFilter;
-            HTMLCollection::create(window.r(), root, filter)
+            HTMLCollection::create(&self.window, root, filter)
         })
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-document-embeds
     fn Embeds(&self) -> Root<HTMLCollection> {
         self.embeds.or_init(|| {
-            let window = self.window.root();
             let root = NodeCast::from_ref(self);
             let filter = box EmbedsFilter;
-            HTMLCollection::create(window.r(), root, filter)
+            HTMLCollection::create(&self.window, root, filter)
         })
     }
 
@@ -1610,40 +1573,36 @@ impl DocumentMethods for Document {
     // https://html.spec.whatwg.org/multipage/#dom-document-links
     fn Links(&self) -> Root<HTMLCollection> {
         self.links.or_init(|| {
-            let window = self.window.root();
             let root = NodeCast::from_ref(self);
             let filter = box LinksFilter;
-            HTMLCollection::create(window.r(), root, filter)
+            HTMLCollection::create(&self.window, root, filter)
         })
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-document-forms
     fn Forms(&self) -> Root<HTMLCollection> {
         self.forms.or_init(|| {
-            let window = self.window.root();
             let root = NodeCast::from_ref(self);
             let filter = box FormsFilter;
-            HTMLCollection::create(window.r(), root, filter)
+            HTMLCollection::create(&self.window, root, filter)
         })
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-document-scripts
     fn Scripts(&self) -> Root<HTMLCollection> {
         self.scripts.or_init(|| {
-            let window = self.window.root();
             let root = NodeCast::from_ref(self);
             let filter = box ScriptsFilter;
-            HTMLCollection::create(window.r(), root, filter)
+            HTMLCollection::create(&self.window, root, filter)
         })
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-document-anchors
     fn Anchors(&self) -> Root<HTMLCollection> {
         self.anchors.or_init(|| {
-            let window = self.window.root();
             let root = NodeCast::from_ref(self);
             let filter = box AnchorsFilter;
-            HTMLCollection::create(window.r(), root, filter)
+            HTMLCollection::create(&self.window, root, filter)
         })
     }
 
@@ -1651,24 +1610,20 @@ impl DocumentMethods for Document {
     fn Applets(&self) -> Root<HTMLCollection> {
         // FIXME: This should be return OBJECT elements containing applets.
         self.applets.or_init(|| {
-            let window = self.window.root();
             let root = NodeCast::from_ref(self);
             let filter = box AppletsFilter;
-            HTMLCollection::create(window.r(), root, filter)
+            HTMLCollection::create(&self.window, root, filter)
         })
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-document-location
     fn Location(&self) -> Root<Location> {
-        let window = self.window.root();
-        let window = window.r();
-        self.location.or_init(|| Location::new(window))
+        self.location.or_init(|| Location::new(&self.window))
     }
 
     // https://dom.spec.whatwg.org/#dom-parentnode-children
     fn Children(&self) -> Root<HTMLCollection> {
-        let window = self.window.root();
-        HTMLCollection::children(window.r(), NodeCast::from_ref(self))
+        HTMLCollection::children(&self.window, NodeCast::from_ref(self))
     }
 
     // https://dom.spec.whatwg.org/#dom-parentnode-firstelementchild
@@ -1725,9 +1680,8 @@ impl DocumentMethods for Document {
         if !is_scheme_host_port_tuple(&url) {
             return Err(Error::Security);
         }
-        let window = self.window.root();
         let (tx, rx) = ipc::channel().unwrap();
-        let _ = window.r().resource_task().send(GetCookiesForUrl((*url).clone(), tx, NonHTTP));
+        let _ = self.window.resource_task().send(GetCookiesForUrl((*url).clone(), tx, NonHTTP));
         let cookies = rx.recv().unwrap();
         Ok(cookies.unwrap_or("".to_owned()))
     }
@@ -1739,8 +1693,7 @@ impl DocumentMethods for Document {
         if !is_scheme_host_port_tuple(url) {
             return Err(Error::Security);
         }
-        let window = self.window.root();
-        let _ = window.r().resource_task().send(SetCookiesForUrl((*url).clone(), cookie, NonHTTP));
+        let _ = self.window.resource_task().send(SetCookiesForUrl((*url).clone(), cookie, NonHTTP));
         Ok(())
     }
 
@@ -1834,9 +1787,8 @@ impl DocumentMethods for Document {
         }
         // Step 4.
         *found = true;
-        let window = self.window();
         let filter = NamedElementFilter { name: name };
-        let collection = HTMLCollection::create(window.r(), root, box filter);
+        let collection = HTMLCollection::create(self.window(), root, box filter);
         collection.r().reflector().get_jsobject().get()
     }
 
@@ -1894,13 +1846,15 @@ impl DocumentProgressHandler {
     fn dispatch_dom_content_loaded(&self) {
         let document = self.addr.root();
         let window = document.r().window();
-        let event = Event::new(GlobalRef::Window(window.r()), "DOMContentLoaded".to_owned(),
+        let event = Event::new(GlobalRef::Window(window), "DOMContentLoaded".to_owned(),
                                EventBubbles::DoesNotBubble,
                                EventCancelable::NotCancelable);
         let doctarget = EventTargetCast::from_ref(document.r());
         let _ = doctarget.DispatchEvent(event.r());
 
-        window.r().reflow(ReflowGoal::ForDisplay, ReflowQueryType::NoQuery, ReflowReason::DOMContentLoaded);
+        window.reflow(ReflowGoal::ForDisplay,
+                      ReflowQueryType::NoQuery,
+                      ReflowReason::DOMContentLoaded);
     }
 
     fn set_ready_state_complete(&self) {
@@ -1911,35 +1865,34 @@ impl DocumentProgressHandler {
     fn dispatch_load(&self) {
         let document = self.addr.root();
         let window = document.r().window();
-        let event = Event::new(GlobalRef::Window(window.r()), "load".to_owned(),
+        let event = Event::new(GlobalRef::Window(window), "load".to_owned(),
                                EventBubbles::DoesNotBubble,
                                EventCancelable::NotCancelable);
-        let wintarget = EventTargetCast::from_ref(window.r());
+        let wintarget = EventTargetCast::from_ref(window);
         let doctarget = EventTargetCast::from_ref(document.r());
         event.r().set_trusted(true);
         let _ = wintarget.dispatch_event_with_target(doctarget, event.r());
 
-        let window_ref = window.r();
-        let browsing_context = window_ref.browsing_context();
+        let browsing_context = window.browsing_context();
         let browsing_context = browsing_context.as_ref().unwrap();
 
-        browsing_context.frame_element().map(|frame_element| {
-            let frame_window = window_from_node(frame_element.r());
+        if let Some(frame_element) = browsing_context.frame_element() {
+            let frame_window = window_from_node(frame_element);
             let event = Event::new(GlobalRef::Window(frame_window.r()), "load".to_owned(),
                                    EventBubbles::DoesNotBubble,
                                    EventCancelable::NotCancelable);
-            let target = EventTargetCast::from_ref(frame_element.r());
+            let target = EventTargetCast::from_ref(frame_element);
             event.r().fire(target);
-        });
+        };
 
         document.r().notify_constellation_load();
 
         // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowserloadend
         document.r().trigger_mozbrowser_event(MozBrowserEvent::LoadEnd);
 
-        window_ref.reflow(ReflowGoal::ForDisplay,
-                          ReflowQueryType::NoQuery,
-                          ReflowReason::DocumentLoaded);
+        window.reflow(ReflowGoal::ForDisplay,
+                      ReflowQueryType::NoQuery,
+                      ReflowReason::DocumentLoaded);
     }
 }
 
@@ -1947,7 +1900,7 @@ impl Runnable for DocumentProgressHandler {
     fn handler(self: Box<DocumentProgressHandler>) {
         let document = self.addr.root();
         let window = document.r().window();
-        if window.r().is_alive() {
+        if window.is_alive() {
             match self.task {
                 DocumentProgressTask::DOMContentLoaded => {
                     self.dispatch_dom_content_loaded();
diff --git a/components/script/dom/domimplementation.rs b/components/script/dom/domimplementation.rs
index d66cba67bc0..93eb8cf8e0a 100644
--- a/components/script/dom/domimplementation.rs
+++ b/components/script/dom/domimplementation.rs
@@ -42,7 +42,7 @@ impl DOMImplementation {
     pub fn new(document: &Document) -> Root<DOMImplementation> {
         let window = document.window();
         reflect_dom_object(box DOMImplementation::new_inherited(document),
-                           GlobalRef::Window(window.r()),
+                           GlobalRef::Window(window),
                            DOMImplementationBinding::Wrap)
     }
 }
@@ -53,20 +53,17 @@ impl DOMImplementationMethods for DOMImplementation {
     fn CreateDocumentType(&self, qualified_name: DOMString, pubid: DOMString, sysid: DOMString)
                           -> Fallible<Root<DocumentType>> {
         try!(validate_qualified_name(&qualified_name));
-        let document = self.document.root();
-        Ok(DocumentType::new(qualified_name, Some(pubid), Some(sysid), document.r()))
+        Ok(DocumentType::new(qualified_name, Some(pubid), Some(sysid), &self.document))
     }
 
     // https://dom.spec.whatwg.org/#dom-domimplementation-createdocument
     fn CreateDocument(&self, namespace: Option<DOMString>, qname: DOMString,
                       maybe_doctype: Option<&DocumentType>) -> Fallible<Root<Document>> {
-        let doc = self.document.root();
-        let doc = doc.r();
-        let win = doc.window();
-        let loader = DocumentLoader::new(&*doc.loader());
+        let win = self.document.window();
+        let loader = DocumentLoader::new(&self.document.loader());
 
         // Step 1.
-        let doc = Document::new(win.r(), None, IsHTMLDocument::NonHTMLDocument,
+        let doc = Document::new(win, None, IsHTMLDocument::NonHTMLDocument,
                                 None, None, DocumentSource::NotFromParser, loader);
         // Step 2-3.
         let maybe_elem = if qname.is_empty() {
@@ -108,13 +105,11 @@ impl DOMImplementationMethods for DOMImplementation {
 
     // https://dom.spec.whatwg.org/#dom-domimplementation-createhtmldocument
     fn CreateHTMLDocument(&self, title: Option<DOMString>) -> Root<Document> {
-        let document = self.document.root();
-        let document = document.r();
-        let win = document.window();
-        let loader = DocumentLoader::new(&*document.loader());
+        let win = self.document.window();
+        let loader = DocumentLoader::new(&self.document.loader());
 
         // Step 1-2.
-        let doc = Document::new(win.r(), None, IsHTMLDocument::HTMLDocument, None, None,
+        let doc = Document::new(win, None, IsHTMLDocument::HTMLDocument, None, None,
                                 DocumentSource::NotFromParser, loader);
 
         {
diff --git a/components/script/dom/domparser.rs b/components/script/dom/domparser.rs
index 8ad9bfa507b..a66b8ea3962 100644
--- a/components/script/dom/domparser.rs
+++ b/components/script/dom/domparser.rs
@@ -49,15 +49,14 @@ impl DOMParserMethods for DOMParser {
                        s: DOMString,
                        ty: DOMParserBinding::SupportedType)
                        -> Fallible<Root<Document>> {
-        let window = self.window.root();
-        let url = window.r().get_url();
+        let url = self.window.get_url();
         let content_type = DOMParserBinding::SupportedTypeValues::strings[ty as usize].to_owned();
-        let doc = window.r().Document();
+        let doc = self.window.Document();
         let doc = doc.r();
         let loader = DocumentLoader::new(&*doc.loader());
         match ty {
             Text_html => {
-                let document = Document::new(window.r(), Some(url.clone()),
+                let document = Document::new(&self.window, Some(url.clone()),
                                              IsHTMLDocument::HTMLDocument,
                                              Some(content_type),
                                              None,
@@ -69,7 +68,7 @@ impl DOMParserMethods for DOMParser {
             }
             Text_xml => {
                 //FIXME: this should probably be FromParser when we actually parse the string (#3756).
-                Ok(Document::new(window.r(), Some(url.clone()),
+                Ok(Document::new(&self.window, Some(url.clone()),
                                  IsHTMLDocument::NonHTMLDocument,
                                  Some(content_type),
                                  None,
diff --git a/components/script/dom/domstringmap.rs b/components/script/dom/domstringmap.rs
index cfa5a8e0a1c..95f727c93cb 100644
--- a/components/script/dom/domstringmap.rs
+++ b/components/script/dom/domstringmap.rs
@@ -37,20 +37,17 @@ impl DOMStringMap {
 impl DOMStringMapMethods for DOMStringMap {
     // https://html.spec.whatwg.org/multipage/#dom-domstringmap-removeitem
     fn NamedDeleter(&self, name: DOMString) {
-        let element = self.element.root();
-        element.r().delete_custom_attr(name)
+        self.element.delete_custom_attr(name)
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-domstringmap-setitem
     fn NamedSetter(&self, name: DOMString, value: DOMString) -> ErrorResult {
-        let element = self.element.root();
-        element.r().set_custom_attr(name, value)
+        self.element.set_custom_attr(name, value)
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-domstringmap-nameditem
     fn NamedGetter(&self, name: DOMString, found: &mut bool) -> DOMString {
-        let element = self.element.root();
-        match element.r().get_custom_attr(name) {
+        match self.element.get_custom_attr(name) {
             Some(value) => {
                 *found = true;
                 value.clone()
diff --git a/components/script/dom/domtokenlist.rs b/components/script/dom/domtokenlist.rs
index e13c1448d70..c3944b7627c 100644
--- a/components/script/dom/domtokenlist.rs
+++ b/components/script/dom/domtokenlist.rs
@@ -39,8 +39,7 @@ impl DOMTokenList {
     }
 
     fn attribute(&self) -> Option<Root<Attr>> {
-        let element = self.element.root();
-        element.r().get_attribute(&ns!(""), &self.local_name)
+        self.element.get_attribute(&ns!(""), &self.local_name)
     }
 
     fn check_token_exceptions(&self, token: &str) -> Fallible<Atom> {
@@ -87,43 +86,40 @@ impl DOMTokenListMethods for DOMTokenList {
 
     // https://dom.spec.whatwg.org/#dom-domtokenlist-add
     fn Add(&self, tokens: Vec<DOMString>) -> ErrorResult {
-        let element = self.element.root();
-        let mut atoms = element.r().get_tokenlist_attribute(&self.local_name);
+        let mut atoms = self.element.get_tokenlist_attribute(&self.local_name);
         for token in &tokens {
             let token = try!(self.check_token_exceptions(&token));
             if !atoms.iter().any(|atom| *atom == token) {
                 atoms.push(token);
             }
         }
-        element.r().set_atomic_tokenlist_attribute(&self.local_name, atoms);
+        self.element.set_atomic_tokenlist_attribute(&self.local_name, atoms);
         Ok(())
     }
 
     // https://dom.spec.whatwg.org/#dom-domtokenlist-remove
     fn Remove(&self, tokens: Vec<DOMString>) -> ErrorResult {
-        let element = self.element.root();
-        let mut atoms = element.r().get_tokenlist_attribute(&self.local_name);
+        let mut atoms = self.element.get_tokenlist_attribute(&self.local_name);
         for token in &tokens {
             let token = try!(self.check_token_exceptions(&token));
             atoms.iter().position(|atom| *atom == token).map(|index| {
                 atoms.remove(index)
             });
         }
-        element.r().set_atomic_tokenlist_attribute(&self.local_name, atoms);
+        self.element.set_atomic_tokenlist_attribute(&self.local_name, atoms);
         Ok(())
     }
 
     // https://dom.spec.whatwg.org/#dom-domtokenlist-toggle
     fn Toggle(&self, token: DOMString, force: Option<bool>) -> Fallible<bool> {
-        let element = self.element.root();
-        let mut atoms = element.r().get_tokenlist_attribute(&self.local_name);
+        let mut atoms = self.element.get_tokenlist_attribute(&self.local_name);
         let token = try!(self.check_token_exceptions(&token));
         match atoms.iter().position(|atom| *atom == token) {
             Some(index) => match force {
                 Some(true) => Ok(true),
                 _ => {
                     atoms.remove(index);
-                    element.r().set_atomic_tokenlist_attribute(&self.local_name, atoms);
+                    self.element.set_atomic_tokenlist_attribute(&self.local_name, atoms);
                     Ok(false)
                 }
             },
@@ -131,7 +127,7 @@ impl DOMTokenListMethods for DOMTokenList {
                 Some(false) => Ok(false),
                 _ => {
                     atoms.push(token);
-                    element.r().set_atomic_tokenlist_attribute(&self.local_name, atoms);
+                    self.element.set_atomic_tokenlist_attribute(&self.local_name, atoms);
                     Ok(true)
                 }
             }
@@ -140,7 +136,7 @@ impl DOMTokenListMethods for DOMTokenList {
 
     // https://dom.spec.whatwg.org/#stringification-behavior
     fn Stringifier(&self) -> DOMString {
-        let tokenlist = self.element.root().r().get_tokenlist_attribute(&self.local_name);
+        let tokenlist = self.element.get_tokenlist_attribute(&self.local_name);
         str_join(&tokenlist, "\x20")
     }
 
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index f6f19fffcfb..3586c239ef4 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -1176,7 +1176,7 @@ impl ElementMethods for Element {
                 node.owner_doc()
             };
             let window = doc.r().window();
-            NamedNodeMap::new(window.r(), self)
+            NamedNodeMap::new(window, self)
         })
     }
 
diff --git a/components/script/dom/htmlimageelement.rs b/components/script/dom/htmlimageelement.rs
index c07022306d6..9e58d68a4e2 100644
--- a/components/script/dom/htmlimageelement.rs
+++ b/components/script/dom/htmlimageelement.rs
@@ -100,7 +100,6 @@ impl HTMLImageElement {
         let node = NodeCast::from_ref(self);
         let document = node.owner_doc();
         let window = document.r().window();
-        let window = window.r();
         let image_cache = window.image_cache_task();
         match value {
             None => {
diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index 5d93d186a07..90cdb5bac6a 100644
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -106,7 +106,7 @@ static DEFAULT_INPUT_SIZE: u32 = 20;
 
 impl HTMLInputElement {
     fn new_inherited(localName: DOMString, prefix: Option<DOMString>, document: &Document) -> HTMLInputElement {
-        let chan = document.window().r().constellation_chan();
+        let chan = document.window().constellation_chan();
         HTMLInputElement {
             htmlelement:
                 HTMLElement::new_inherited_with_state(IN_ENABLED_STATE,
@@ -759,17 +759,16 @@ impl Activatable for HTMLInputElement {
             InputType::InputRadio => {
                 // We want to restore state only if the element had been changed in the first place
                 if cache.was_mutable {
-                    let old_checked = cache.checked_radio.as_ref().map(|t| t.root());
                     let name = self.get_radio_group_name();
-                    match old_checked {
-                        Some(ref o) => {
+                    match cache.checked_radio.as_ref().map(|t| &*t) {
+                        Some(o) => {
                             // Avoiding iterating through the whole tree here, instead
                             // we can check if the conditions for radio group siblings apply
-                            if name == o.r().get_radio_group_name() && // TODO should be compatibility caseless
-                               self.form_owner() == o.r().form_owner() &&
+                            if name == o.get_radio_group_name() && // TODO should be compatibility caseless
+                               self.form_owner() == o.form_owner() &&
                                // TODO Both a and b are in the same home subtree
-                               o.r().input_type.get() == InputType::InputRadio {
-                                    o.r().SetChecked(true);
+                               o.input_type.get() == InputType::InputRadio {
+                                    o.SetChecked(true);
                             } else {
                                 self.SetChecked(false);
                             }
diff --git a/components/script/dom/htmlscriptelement.rs b/components/script/dom/htmlscriptelement.rs
index b6f9e97e712..579fe0c7c1b 100644
--- a/components/script/dom/htmlscriptelement.rs
+++ b/components/script/dom/htmlscriptelement.rs
@@ -209,7 +209,7 @@ impl HTMLScriptElement {
         // Step 10.
         let document_from_node_ref = document_from_node(self);
         let document_from_node_ref = document_from_node_ref.r();
-        if self.parser_inserted.get() && self.parser_document.root().r() != document_from_node_ref {
+        if self.parser_inserted.get() && &*self.parser_document != document_from_node_ref {
             return NextParserState::Continue;
         }
 
diff --git a/components/script/dom/htmltextareaelement.rs b/components/script/dom/htmltextareaelement.rs
index 8982fda94a1..ba46c064762 100644
--- a/components/script/dom/htmltextareaelement.rs
+++ b/components/script/dom/htmltextareaelement.rs
@@ -84,7 +84,7 @@ impl HTMLTextAreaElement {
     fn new_inherited(localName: DOMString,
                      prefix: Option<DOMString>,
                      document: &Document) -> HTMLTextAreaElement {
-        let chan = document.window().r().constellation_chan();
+        let chan = document.window().constellation_chan();
         HTMLTextAreaElement {
             htmlelement:
                 HTMLElement::new_inherited_with_state(IN_ENABLED_STATE,
diff --git a/components/script/dom/location.rs b/components/script/dom/location.rs
index c366139649b..230cf2748da 100644
--- a/components/script/dom/location.rs
+++ b/components/script/dom/location.rs
@@ -35,33 +35,31 @@ impl Location {
     }
 
     fn get_url(&self) -> Url {
-        self.window.root().get_url()
+        self.window.get_url()
     }
 
     fn set_url_component(&self, value: USVString,
                          setter: fn(&mut Url, USVString)) {
-        let window = self.window.root();
-        let mut url = window.get_url();
+        let mut url = self.window.get_url();
         setter(&mut url, value);
-        window.load_url(url);
+        self.window.load_url(url);
     }
 }
 
 impl LocationMethods for Location {
     // https://html.spec.whatwg.org/multipage/#dom-location-assign
     fn Assign(&self, url: DOMString) {
-        let window = self.window.root();
         // TODO: per spec, we should use the _API base URL_ specified by the
         //       _entry settings object_.
-        let base_url = window.get_url();
+        let base_url = self.window.get_url();
         if let Ok(url) = UrlParser::new().base_url(&base_url).parse(&url) {
-            window.load_url(url);
+            self.window.load_url(url);
         }
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-location-reload
     fn Reload(&self) {
-        self.window.root().load_url(self.get_url());
+        self.window.load_url(self.get_url());
     }
 
     // https://url.spec.whatwg.org/#dom-urlutils-hash
@@ -101,9 +99,8 @@ impl LocationMethods for Location {
 
     // https://url.spec.whatwg.org/#dom-urlutils-href
     fn SetHref(&self, value: USVString) -> ErrorResult {
-        let window = self.window.root();
-        if let Ok(url) = UrlParser::new().base_url(&window.get_url()).parse(&value.0) {
-            window.load_url(url);
+        if let Ok(url) = UrlParser::new().base_url(&self.window.get_url()).parse(&value.0) {
+            self.window.load_url(url);
         };
         Ok(())
     }
diff --git a/components/script/dom/namednodemap.rs b/components/script/dom/namednodemap.rs
index 078ddcc0d84..6070c0bb0c2 100644
--- a/components/script/dom/namednodemap.rs
+++ b/components/script/dom/namednodemap.rs
@@ -37,57 +37,38 @@ impl NamedNodeMap {
 impl NamedNodeMapMethods for NamedNodeMap {
     // https://dom.spec.whatwg.org/#dom-namednodemap-length
     fn Length(&self) -> u32 {
-        let owner = self.owner.root();
-        // FIXME(https://github.com/rust-lang/rust/issues/23338)
-        let owner = owner.r();
-        let attrs = owner.attrs();
-        attrs.len() as u32
+        self.owner.attrs().len() as u32
     }
 
     // https://dom.spec.whatwg.org/#dom-namednodemap-item
     fn Item(&self, index: u32) -> Option<Root<Attr>> {
-        let owner = self.owner.root();
-        // FIXME(https://github.com/rust-lang/rust/issues/23338)
-        let owner = owner.r();
-        let attrs = owner.attrs();
-        attrs.get(index as usize).map(|t| t.root())
+        self.owner.attrs().get(index as usize).map(JS::root)
     }
 
     // https://dom.spec.whatwg.org/#dom-namednodemap-getnameditem
     fn GetNamedItem(&self, name: DOMString) -> Option<Root<Attr>> {
-        let owner = self.owner.root();
-        // FIXME(https://github.com/rust-lang/rust/issues/23338)
-        let owner = owner.r();
-        owner.get_attribute_by_name(name)
+        self.owner.get_attribute_by_name(name)
     }
 
     // https://dom.spec.whatwg.org/#dom-namednodemap-getnameditemns
     fn GetNamedItemNS(&self, namespace: Option<DOMString>, local_name: DOMString)
                      -> Option<Root<Attr>> {
-        let owner = self.owner.root();
-        // FIXME(https://github.com/rust-lang/rust/issues/23338)
-        let owner = owner.r();
         let ns = namespace_from_domstring(namespace);
-        owner.get_attribute(&ns, &Atom::from_slice(&local_name))
+        self.owner.get_attribute(&ns, &Atom::from_slice(&local_name))
     }
 
     // https://dom.spec.whatwg.org/#dom-namednodemap-removenameditem
     fn RemoveNamedItem(&self, name: DOMString) -> Fallible<Root<Attr>> {
-        let owner = self.owner.root();
-        // FIXME(https://github.com/rust-lang/rust/issues/23338)
-        let owner = owner.r();
-        let name = owner.parsed_name(name);
-        owner.remove_attribute_by_name(&name).ok_or(Error::NotFound)
+        let name = self.owner.parsed_name(name);
+        self.owner.remove_attribute_by_name(&name).ok_or(Error::NotFound)
     }
 
     // https://dom.spec.whatwg.org/#dom-namednodemap-removenameditemns
     fn RemoveNamedItemNS(&self, namespace: Option<DOMString>, local_name: DOMString)
                       -> Fallible<Root<Attr>> {
-        let owner = self.owner.root();
-        // FIXME(https://github.com/rust-lang/rust/issues/23338)
-        let owner = owner.r();
         let ns = namespace_from_domstring(namespace);
-        owner.remove_attribute(&ns, &Atom::from_slice(&local_name)).ok_or(Error::NotFound)
+        self.owner.remove_attribute(&ns, &Atom::from_slice(&local_name))
+            .ok_or(Error::NotFound)
     }
 
     // https://dom.spec.whatwg.org/#dom-namednodemap-item
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index 36f6fd04bcc..034b8dfc3db 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -1308,7 +1308,7 @@ impl Node {
              wrap_fn:   extern "Rust" fn(*mut JSContext, GlobalRef, Box<N>) -> Root<N>)
              -> Root<N> {
         let window = document.window();
-        reflect_dom_object(node, GlobalRef::Window(window.r()), wrap_fn)
+        reflect_dom_object(node, GlobalRef::Window(window), wrap_fn)
     }
 
     pub fn new_inherited(doc: &Document) -> Node {
@@ -1651,7 +1651,7 @@ impl Node {
                 };
                 let window = document.window();
                 let loader = DocumentLoader::new(&*document.loader());
-                let document = Document::new(window.r(), Some((*document.url()).clone()),
+                let document = Document::new(window, Some((*document.url()).clone()),
                                              is_html_doc, None,
                                              None, DocumentSource::NotFromParser, loader);
                 NodeCast::from_root(document)
@@ -1892,7 +1892,7 @@ impl NodeMethods for Node {
         self.child_list.or_init(|| {
             let doc = self.owner_doc();
             let window = doc.r().window();
-            NodeList::new_child_list(window.r(), self)
+            NodeList::new_child_list(window, self)
         })
     }
 
@@ -2391,7 +2391,7 @@ pub fn document_from_node<T: NodeBase + Reflectable>(derived: &T) -> Root<Docume
 
 pub fn window_from_node<T: NodeBase + Reflectable>(derived: &T) -> Root<Window> {
     let document = document_from_node(derived);
-    document.r().window()
+    Root::from_ref(document.r().window())
 }
 
 impl VirtualMethods for Node {
diff --git a/components/script/dom/nodeiterator.rs b/components/script/dom/nodeiterator.rs
index c7152231776..27a99ec3b55 100644
--- a/components/script/dom/nodeiterator.rs
+++ b/components/script/dom/nodeiterator.rs
@@ -47,9 +47,8 @@ impl NodeIterator {
                            root_node: &Node,
                            what_to_show: u32,
                            filter: Filter) -> Root<NodeIterator> {
-        let window = document.window();
         reflect_dom_object(box NodeIterator::new_inherited(root_node, what_to_show, filter),
-                           GlobalRef::Window(window.r()),
+                           GlobalRef::Window(document.window()),
                            NodeIteratorBinding::Wrap)
     }
 
@@ -122,7 +121,7 @@ impl NodeIteratorMethods for NodeIterator {
         }
 
         // Step 3-1.
-        for following_node in node.r().following_nodes(self.root_node.root().r()) {
+        for following_node in node.r().following_nodes(&self.root_node) {
             // Step 3-2.
             let result = try!(self.accept_node(following_node.r()));
 
@@ -166,7 +165,7 @@ impl NodeIteratorMethods for NodeIterator {
         }
 
         // Step 3-1.
-        for preceding_node in node.r().preceding_nodes(self.root_node.root().r()) {
+        for preceding_node in node.r().preceding_nodes(&self.root_node) {
 
             // Step 3-2.
             let result = try!(self.accept_node(preceding_node.r()));
diff --git a/components/script/dom/nodelist.rs b/components/script/dom/nodelist.rs
index b5db05945ca..2ed127dd2dc 100644
--- a/components/script/dom/nodelist.rs
+++ b/components/script/dom/nodelist.rs
@@ -109,7 +109,7 @@ impl ChildrenList {
     }
 
     pub fn len(&self) -> u32 {
-        self.node.root().children_count()
+        self.node.children_count()
     }
 
     pub fn item(&self, index: u32) -> Option<Root<Node>> {
@@ -121,7 +121,7 @@ impl ChildrenList {
         }
         if index == 0u32 {
             // Item is first child if any, not worth updating last visited.
-            return self.node.root().GetFirstChild();
+            return self.node.GetFirstChild();
         }
         let last_index = self.last_index.get();
         if index == last_index {
@@ -137,7 +137,7 @@ impl ChildrenList {
         } else if index > last_index {
             if index == len - 1u32 {
                 // Item is parent's last child, not worth updating last visited.
-                return Some(self.node.root().GetLastChild().unwrap());
+                return Some(self.node.GetLastChild().unwrap());
             }
             if index <= last_index + (len - last_index) / 2u32 {
                 // Item is closer to the last visited child and follows it.
@@ -147,7 +147,7 @@ impl ChildrenList {
             } else {
                 // Item is closer to parent's last child and obviously
                 // precedes it.
-                self.node.root().GetLastChild().unwrap()
+                self.node.GetLastChild().unwrap()
                     .inclusively_preceding_siblings()
                     .nth((len - index - 1u32) as usize).unwrap()
             }
@@ -159,7 +159,7 @@ impl ChildrenList {
         } else {
             // Item is closer to parent's first child and obviously follows it.
             debug_assert!(index < last_index / 2u32);
-            self.node.root().GetFirstChild().unwrap()
+            self.node.GetFirstChild().unwrap()
                      .inclusively_following_siblings()
                      .nth(index as usize)
                      .unwrap()
@@ -263,7 +263,7 @@ impl ChildrenList {
     }
 
     fn reset(&self) {
-        self.last_visited.set(self.node.root().GetFirstChild().as_ref().map(Root::r));
+        self.last_visited.set(self.node.GetFirstChild().r());
         self.last_index.set(0u32);
     }
 }
diff --git a/components/script/dom/performance.rs b/components/script/dom/performance.rs
index 2d0a5990cdc..b8b6c17ef09 100644
--- a/components/script/dom/performance.rs
+++ b/components/script/dom/performance.rs
@@ -51,7 +51,7 @@ impl PerformanceMethods for Performance {
 
     // https://dvcs.w3.org/hg/webperf/raw-file/tip/specs/HighResolutionTime/Overview.html#dom-performance-now
     fn Now(&self) -> DOMHighResTimeStamp {
-        let navStart = self.timing.root().r().NavigationStartPrecise();
+        let navStart = self.timing.NavigationStartPrecise();
         let now = (time::precise_time_ns() as f64 - navStart) / 1000000 as f64;
         Finite::wrap(now)
     }
diff --git a/components/script/dom/range.rs b/components/script/dom/range.rs
index 0b9a5cc0dbf..52ab9d24d66 100644
--- a/components/script/dom/range.rs
+++ b/components/script/dom/range.rs
@@ -49,10 +49,9 @@ impl Range {
                start_container: &Node, start_offset: u32,
                end_container: &Node, end_offset: u32)
                -> Root<Range> {
-        let window = document.window();
         reflect_dom_object(box Range::new_inherited(start_container, start_offset,
                                                     end_container, end_offset),
-                           GlobalRef::Window(window.r()),
+                           GlobalRef::Window(document.window()),
                            RangeBinding::Wrap)
     }
 
diff --git a/components/script/dom/servohtmlparser.rs b/components/script/dom/servohtmlparser.rs
index 9b319e66a9a..2cf4bac0a4c 100644
--- a/components/script/dom/servohtmlparser.rs
+++ b/components/script/dom/servohtmlparser.rs
@@ -15,7 +15,7 @@ use dom::bindings::refcounted::Trusted;
 use dom::bindings::trace::JSTraceable;
 use dom::bindings::utils::{Reflector, reflect_dom_object};
 use dom::document::Document;
-use dom::node::{Node, window_from_node};
+use dom::node::Node;
 use dom::text::Text;
 use dom::window::Window;
 use encoding::all::UTF_8;
@@ -48,8 +48,7 @@ impl Sink {
         match child {
             NodeOrText::AppendNode(n) => n.root(),
             NodeOrText::AppendText(t) => {
-                let doc = self.document.root();
-                let text = Text::new(t.into(), &doc);
+                let text = Text::new(t.into(), &self.document);
                 NodeCast::from_root(text)
             }
         }
@@ -109,7 +108,7 @@ impl AsyncResponseListener for ParserContext {
 
         let parser = parser.r();
         let win = parser.window();
-        self.parser = Some(Trusted::new(win.r().get_cx(), parser, self.script_chan.clone()));
+        self.parser = Some(Trusted::new(win.get_cx(), parser, self.script_chan.clone()));
 
         match content_type {
             Some(ContentType(Mime(TopLevel::Image, _, _))) => {
@@ -153,8 +152,7 @@ impl AsyncResponseListener for ParserContext {
             Some(parser) => parser.root(),
             None => return,
         };
-        let doc = parser.r().document.root();
-        doc.r().finish_load(LoadType::PageSource(self.url.clone()));
+        parser.document.finish_load(LoadType::PageSource(self.url.clone()));
 
         if let Err(err) = status {
             debug!("Failed to load page URL {}, error: {}", self.url.serialize(), err);
@@ -189,7 +187,7 @@ pub struct ServoHTMLParser {
 
 impl<'a> Parser for &'a ServoHTMLParser {
     fn parse_chunk(self, input: String) {
-        self.document.root().r().set_current_parser(Some(self));
+        self.document.set_current_parser(Some(self));
         self.pending_input.borrow_mut().push(input);
         self.parse_sync();
     }
@@ -201,8 +199,7 @@ impl<'a> Parser for &'a ServoHTMLParser {
         self.tokenizer().borrow_mut().end();
         debug!("finished parsing");
 
-        let document = self.document.root();
-        document.r().set_current_parser(None);
+        self.document.set_current_parser(None);
 
         if let Some(pipeline) = self.pipeline {
             ScriptTask::parsing_complete(pipeline);
@@ -214,7 +211,6 @@ impl ServoHTMLParser {
     #[allow(unrooted_must_root)]
     pub fn new(base_url: Option<Url>, document: &Document, pipeline: Option<PipelineId>)
                -> Root<ServoHTMLParser> {
-        let window = document.window();
         let sink = Sink {
             base_url: base_url,
             document: JS::from_ref(document),
@@ -237,14 +233,13 @@ impl ServoHTMLParser {
             pipeline: pipeline,
         };
 
-        reflect_dom_object(box parser, GlobalRef::Window(window.r()),
+        reflect_dom_object(box parser, GlobalRef::Window(document.window()),
                            ServoHTMLParserBinding::Wrap)
     }
 
     #[allow(unrooted_must_root)]
     pub fn new_for_fragment(base_url: Option<Url>, document: &Document,
                             fragment_context: FragmentContext) -> Root<ServoHTMLParser> {
-        let window = document.window();
         let sink = Sink {
             base_url: base_url,
             document: JS::from_ref(document),
@@ -275,7 +270,7 @@ impl ServoHTMLParser {
             pipeline: None,
         };
 
-        reflect_dom_object(box parser, GlobalRef::Window(window.r()),
+        reflect_dom_object(box parser, GlobalRef::Window(document.window()),
                            ServoHTMLParserBinding::Wrap)
     }
 
@@ -301,8 +296,7 @@ impl ServoHTMLParser {
                 break;
             }
 
-            let document = self.document.root();
-            document.r().reflow_if_reflow_timer_expired();
+            self.document.reflow_if_reflow_timer_expired();
 
             let mut pending_input = self.pending_input.borrow_mut();
             if !pending_input.is_empty() {
@@ -320,9 +314,8 @@ impl ServoHTMLParser {
         }
     }
 
-    fn window(&self) -> Root<Window> {
-        let doc = self.document.root();
-        window_from_node(doc.r())
+    fn window(&self) -> &Window {
+        self.document.window()
     }
 }
 
diff --git a/components/script/dom/treewalker.rs b/components/script/dom/treewalker.rs
index 7f4646a1618..f19e8383ddf 100644
--- a/components/script/dom/treewalker.rs
+++ b/components/script/dom/treewalker.rs
@@ -45,9 +45,8 @@ impl TreeWalker {
                            root_node: &Node,
                            what_to_show: u32,
                            filter: Filter) -> Root<TreeWalker> {
-        let window = document.window();
         reflect_dom_object(box TreeWalker::new_inherited(root_node, what_to_show, filter),
-                           GlobalRef::Window(window.r()),
+                           GlobalRef::Window(document.window()),
                            TreeWalkerBinding::Wrap)
     }
 
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 7172177af77..b3968a9205d 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -381,7 +381,7 @@ impl WindowMethods for Window {
 
     // https://html.spec.whatwg.org/multipage/#dom-document-0
     fn Document(&self) -> Root<Document> {
-        self.browsing_context().as_ref().unwrap().active_document()
+        Root::from_ref(self.browsing_context().as_ref().unwrap().active_document())
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-location
@@ -411,7 +411,7 @@ impl WindowMethods for Window {
 
     // https://html.spec.whatwg.org/multipage/#dom-frameelement
     fn GetFrameElement(&self) -> Option<Root<Element>> {
-        self.browsing_context().as_ref().unwrap().frame_element()
+        self.browsing_context().as_ref().unwrap().frame_element().map(Root::from_ref)
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-navigator
@@ -1248,11 +1248,11 @@ impl Window {
         let browsing_context = browsing_context.as_ref().unwrap();
 
         browsing_context.frame_element().map(|frame_element| {
-            let window = window_from_node(frame_element.r());
+            let window = window_from_node(frame_element);
             // FIXME(https://github.com/rust-lang/rust/issues/23338)
             let r = window.r();
             let context = r.browsing_context();
-            context.as_ref().unwrap().active_window()
+            Root::from_ref(context.as_ref().unwrap().active_window())
         })
     }
 }
diff --git a/components/script/dom/xmlhttprequest.rs b/components/script/dom/xmlhttprequest.rs
index 3373865fa5f..400b06ca95f 100644
--- a/components/script/dom/xmlhttprequest.rs
+++ b/components/script/dom/xmlhttprequest.rs
@@ -493,8 +493,7 @@ impl XMLHttpRequestMethods for XMLHttpRequest {
 
         if !self.sync.get() {
             // Step 8
-            let upload_target = self.upload.root();
-            let event_target = EventTargetCast::from_ref(upload_target.r());
+            let event_target = EventTargetCast::from_ref(&*self.upload);
             if event_target.has_handlers() {
                 self.upload_events.set(true);
             }
@@ -917,13 +916,12 @@ impl XMLHttpRequest {
 
     fn dispatch_progress_event(&self, upload: bool, type_: DOMString, loaded: u64, total: Option<u64>) {
         let global = self.global.root();
-        let upload_target = self.upload.root();
         let progressevent = ProgressEvent::new(global.r(),
                                                type_, EventBubbles::DoesNotBubble, EventCancelable::NotCancelable,
                                                total.is_some(), loaded,
                                                total.unwrap_or(0));
         let target = if upload {
-            EventTargetCast::from_ref(upload_target.r())
+            EventTargetCast::from_ref(&*self.upload)
         } else {
             EventTargetCast::from_ref(self)
         };