Auto merge of #29374 - jdm:get-cx-cleanup, r=mrobinson

Assert if DomObject::global is called outside of a JS realm

To avoid crashing in https://github.com/servo/servo/issues/27037, we need to progressively add `InRealm` or `AlreadyInRealm` arguments higher up in the call stack. These changes assert that DomObject::global is only called inside of a realm, which is preferable to segfaulting in the JS engine. Making this a compile-time error requires changing lots of `.global()` callsites, but this PR removes a bunch that are now unnecessary.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix (partially) #27037
- [x] There are tests for these changes

components/script/body.rs

@@ -718,10 +718,8 @@ impl Callback for ConsumeBodyPromiseHandler {
 // https://fetch.spec.whatwg.org/#concept-body-consume-body
 #[allow(unrooted_must_root)]
 pub fn consume_body<T: BodyMixin + DomObject>(object: &T, body_type: BodyType) -> Rc<Promise> {
-    let global = object.global();
+    let in_realm_proof = AlreadyInRealm::assert();
-    let in_realm_proof = AlreadyInRealm::assert(&global);
+    let promise = Promise::new_in_current_realm(InRealm::Already(&in_realm_proof));
-    let promise =
-        Promise::new_in_current_realm(&object.global(), InRealm::Already(&in_realm_proof));
 
     // Step 1
     if object.is_disturbed() || object.is_locked() {

components/script/devtools.rs

@@ -33,7 +33,7 @@ use uuid::Uuid;
 pub fn handle_evaluate_js(global: &GlobalScope, eval: String, reply: IpcSender<EvaluateJSReply>) {
     // global.get_cx() returns a valid `JSContext` pointer, so this is safe.
     let result = unsafe {
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         let _ac = enter_realm(global);
         rooted!(in(*cx) let mut rval = UndefinedValue());
         let source_code = SourceCode::Text(Rc::new(DOMString::from_string(eval)));

components/script/dom/abstractworkerglobalscope.rs

@@ -9,6 +9,7 @@ use crate::dom::dedicatedworkerglobalscope::{AutoWorkerReset, DedicatedWorkerScr
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::worker::TrustedWorkerAddress;
 use crate::dom::workerglobalscope::WorkerGlobalScope;
+use crate::realms::enter_realm;
 use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptPort};
 use crate::task_queue::{QueuedTaskConversion, TaskQueue};
 use crossbeam_channel::{Receiver, Sender};
@@ -140,6 +141,7 @@ pub fn run_worker_event_loop<T, WorkerMsg, Event>(
     }
     // Step 3
     for event in sequential {
+        let _realm = enter_realm(&*worker_scope);
         if !worker_scope.handle_event(event) {
             // Shutdown
             return;

components/script/dom/audiobuffer.rs

@@ -9,8 +9,9 @@ use crate::dom::bindings::codegen::Bindings::AudioBufferBinding::{
 };
 use crate::dom::bindings::error::{Error, Fallible};
 use crate::dom::bindings::num::Finite;
-use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
+use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
 use crate::dom::bindings::root::DomRoot;
+use crate::dom::globalscope::GlobalScope;
 use crate::dom::window::Window;
 use crate::realms::enter_realm;
 use crate::script_runtime::JSContext;
@@ -172,7 +173,7 @@ impl AudioBuffer {
             self.length as usize,
             self.sample_rate,
         );
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         for (i, channel) in self.js_channels.borrow_mut().iter().enumerate() {
             // Step 1.
             if channel.get().is_null() {
@@ -271,7 +272,7 @@ impl AudioBufferMethods for AudioBuffer {
         }
 
         let bytes_to_copy = min(self.length - start_in_channel, destination.len() as u32) as usize;
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         let channel_number = channel_number as usize;
         let offset = start_in_channel as usize;
         let mut dest = Vec::with_capacity(destination.len());
@@ -313,7 +314,7 @@ impl AudioBufferMethods for AudioBuffer {
             return Err(Error::IndexSize);
         }
 
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         if !self.restore_js_channel_data(cx) {
             return Err(Error::JSFailed);
         }

components/script/dom/audiocontext.rs

@@ -132,7 +132,7 @@ impl AudioContextMethods for AudioContext {
     // https://webaudio.github.io/web-audio-api/#dom-audiocontext-suspend
     fn Suspend(&self, comp: InRealm) -> Rc<Promise> {
         // Step 1.
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
 
         // Step 2.
         if self.context.control_thread_state() == ProcessingState::Closed {
@@ -193,7 +193,7 @@ impl AudioContextMethods for AudioContext {
     // https://webaudio.github.io/web-audio-api/#dom-audiocontext-close
     fn Close(&self, comp: InRealm) -> Rc<Promise> {
         // Step 1.
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
 
         // Step 2.
         if self.context.control_thread_state() == ProcessingState::Closed {

components/script/dom/baseaudiocontext.rs

@@ -284,7 +284,7 @@ impl BaseAudioContextMethods for BaseAudioContext {
     /// https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-resume
     fn Resume(&self, comp: InRealm) -> Rc<Promise> {
         // Step 1.
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
 
         // Step 2.
         if self.audio_context_impl.lock().unwrap().state() == ProcessingState::Closed {
@@ -440,7 +440,7 @@ impl BaseAudioContextMethods for BaseAudioContext {
         comp: InRealm,
     ) -> Rc<Promise> {
         // Step 1.
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
         let global = self.global();
         let window = global.as_window();
 

components/script/dom/bindings/callback.rs

@@ -245,7 +245,7 @@ impl CallSetup {
         if let Some(window) = global.downcast::<Window>() {
             window.Document().ensure_safe_to_run_script_or_layout();
         }
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
 
         let aes = AutoEntryScript::new(&global);
         let ais = callback.incumbent().map(AutoIncumbentScript::new);

components/script/dom/bindings/reflector.rs

@@ -9,6 +9,7 @@ use crate::dom::bindings::iterable::{Iterable, IterableIterator};
 use crate::dom::bindings::root::{Dom, DomRoot, Root};
 use crate::dom::bindings::trace::JSTraceable;
 use crate::dom::globalscope::GlobalScope;
+use crate::realms::AlreadyInRealm;
 use crate::script_runtime::JSContext;
 use js::jsapi::{Heap, JSObject};
 use js::rust::HandleObject;
@@ -22,7 +23,7 @@ where
     U: DerivedFrom<GlobalScope>,
 {
     let global_scope = global.upcast();
-    unsafe { T::WRAP(global_scope.get_cx(), global_scope, obj) }
+    unsafe { T::WRAP(GlobalScope::get_cx(), global_scope, obj) }
 }
 
 /// A struct to store a reference to the reflector of a DOM object.
@@ -82,7 +83,8 @@ pub trait DomObject: JSTraceable + 'static {
     where
         Self: Sized,
     {
-        GlobalScope::from_reflector(self)
+        let realm = AlreadyInRealm::assert_for_cx(GlobalScope::get_cx());
+        GlobalScope::from_reflector(self, &realm)
     }
 }
 

components/script/dom/bindings/structuredclone.rs

@@ -352,7 +352,7 @@ pub fn read(
     mut data: StructuredSerializedData,
     rval: MutableHandleValue,
 ) -> Result<Vec<DomRoot<MessagePort>>, ()> {
-    let cx = global.get_cx();
+    let cx = GlobalScope::get_cx();
     let _ac = enter_realm(&*global);
     let mut sc_holder = StructuredDataHolder::Read {
         blobs: None,

components/script/dom/blob.rs

@@ -238,8 +238,8 @@ impl BlobMethods for Blob {
     // https://w3c.github.io/FileAPI/#text-method-algo
     fn Text(&self) -> Rc<Promise> {
         let global = self.global();
-        let in_realm_proof = AlreadyInRealm::assert(&global);
+        let in_realm_proof = AlreadyInRealm::assert();
-        let p = Promise::new_in_current_realm(&global, InRealm::Already(&in_realm_proof));
+        let p = Promise::new_in_current_realm(InRealm::Already(&in_realm_proof));
         let id = self.get_blob_url_id();
         global.read_file_async(
             id,
@@ -261,8 +261,8 @@ impl BlobMethods for Blob {
     // https://w3c.github.io/FileAPI/#arraybuffer-method-algo
     fn ArrayBuffer(&self) -> Rc<Promise> {
         let global = self.global();
-        let in_realm_proof = AlreadyInRealm::assert(&global);
+        let in_realm_proof = AlreadyInRealm::assert();
-        let p = Promise::new_in_current_realm(&global, InRealm::Already(&in_realm_proof));
+        let p = Promise::new_in_current_realm(InRealm::Already(&in_realm_proof));
 
         let id = self.get_blob_url_id();
 
@@ -272,7 +272,7 @@ impl BlobMethods for Blob {
             Box::new(|promise, bytes| {
                 match bytes {
                     Ok(b) => {
-                        let cx = promise.global().get_cx();
+                        let cx = GlobalScope::get_cx();
                         let result = run_array_buffer_data_algorithm(cx, b);
 
                         match result {

components/script/dom/bluetooth.rs

@@ -287,8 +287,8 @@ where
     T: AsyncBluetoothListener + DomObject + 'static,
     F: FnOnce(StringOrUnsignedLong) -> Fallible<UUID>,
 {
-    let in_realm_proof = AlreadyInRealm::assert(&attribute.global());
+    let in_realm_proof = AlreadyInRealm::assert();
-    let p = Promise::new_in_current_realm(&attribute.global(), InRealm::Already(&in_realm_proof));
+    let p = Promise::new_in_current_realm(InRealm::Already(&in_realm_proof));
 
     let result_uuid = if let Some(u) = uuid {
         // Step 1.
@@ -528,7 +528,7 @@ impl From<BluetoothError> for Error {
 impl BluetoothMethods for Bluetooth {
     // https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetooth-requestdevice
     fn RequestDevice(&self, option: &RequestDeviceOptions, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         // Step 1.
         if (option.filters.is_some() && option.acceptAllDevices) ||
             (option.filters.is_none() && !option.acceptAllDevices)
@@ -546,7 +546,7 @@ impl BluetoothMethods for Bluetooth {
 
     // https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetooth-getavailability
     fn GetAvailability(&self, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         // Step 1. We did not override the method
         // Step 2 - 3. in handle_response
         let sender = response_async(&p, self);

components/script/dom/bluetoothdevice.rs

@@ -277,7 +277,7 @@ impl BluetoothDeviceMethods for BluetoothDevice {
 
     // https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetoothdevice-watchadvertisements
     fn WatchAdvertisements(&self, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         let sender = response_async(&p, self);
         // TODO: Step 1.
         // Note: Steps 2 - 3 are implemented in components/bluetooth/lib.rs in watch_advertisements function

components/script/dom/bluetoothremotegattcharacteristic.rs

@@ -137,7 +137,7 @@ impl BluetoothRemoteGATTCharacteristicMethods for BluetoothRemoteGATTCharacteris
 
     // https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetoothremotegattcharacteristic-readvalue
     fn ReadValue(&self, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
 
         // Step 1.
         if uuid_is_blocklisted(self.uuid.as_ref(), Blocklist::Reads) {
@@ -170,7 +170,7 @@ impl BluetoothRemoteGATTCharacteristicMethods for BluetoothRemoteGATTCharacteris
 
     // https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetoothremotegattcharacteristic-writevalue
     fn WriteValue(&self, value: ArrayBufferViewOrArrayBuffer, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
 
         // Step 1.
         if uuid_is_blocklisted(self.uuid.as_ref(), Blocklist::Writes) {
@@ -221,7 +221,7 @@ impl BluetoothRemoteGATTCharacteristicMethods for BluetoothRemoteGATTCharacteris
 
     // https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetoothremotegattcharacteristic-startnotifications
     fn StartNotifications(&self, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
 
         // Step 1.
         if uuid_is_blocklisted(self.uuid.as_ref(), Blocklist::Reads) {
@@ -258,7 +258,7 @@ impl BluetoothRemoteGATTCharacteristicMethods for BluetoothRemoteGATTCharacteris
 
     // https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetoothremotegattcharacteristic-stopnotifications
     fn StopNotifications(&self, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         let sender = response_async(&p, self);
 
         // TODO: Step 3 - 4: Implement `active notification context set` for BluetoothRemoteGATTCharacteristic,

components/script/dom/bluetoothremotegattdescriptor.rs

@@ -93,7 +93,7 @@ impl BluetoothRemoteGATTDescriptorMethods for BluetoothRemoteGATTDescriptor {
 
     // https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetoothremotegattdescriptor-readvalue
     fn ReadValue(&self, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
 
         // Step 1.
         if uuid_is_blocklisted(self.uuid.as_ref(), Blocklist::Reads) {
@@ -125,7 +125,7 @@ impl BluetoothRemoteGATTDescriptorMethods for BluetoothRemoteGATTDescriptor {
 
     // https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetoothremotegattdescriptor-writevalue
     fn WriteValue(&self, value: ArrayBufferViewOrArrayBuffer, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
 
         // Step 1.
         if uuid_is_blocklisted(self.uuid.as_ref(), Blocklist::Writes) {

components/script/dom/bluetoothremotegattserver.rs

@@ -71,7 +71,7 @@ impl BluetoothRemoteGATTServerMethods for BluetoothRemoteGATTServer {
     #[allow(unsafe_code)]
     fn Connect(&self, comp: InRealm) -> Rc<Promise> {
         // Step 1.
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         let sender = response_async(&p, self);
 
         // TODO: Step 3: Check if the UA is currently using the Bluetooth system.

components/script/dom/console.rs

@@ -17,7 +17,8 @@ impl Console {
     #[allow(unsafe_code)]
     fn send_to_devtools(global: &GlobalScope, level: LogLevel, message: DOMString) {
         if let Some(chan) = global.devtools_chan() {
-            let caller = unsafe { describe_scripted_caller(*global.get_cx()) }.unwrap_or_default();
+            let caller =
+                unsafe { describe_scripted_caller(*GlobalScope::get_cx()) }.unwrap_or_default();
             let console_message = ConsoleMessage {
                 message: String::from(message),
                 logLevel: level,

components/script/dom/create.rs

@@ -154,7 +154,7 @@ fn create_html_element(
                             // Step 6. Recovering from exception.
                             let global =
                                 GlobalScope::current().unwrap_or_else(|| document.global());
-                            let cx = global.get_cx();
+                            let cx = GlobalScope::get_cx();
 
                             // Step 6.1.1
                             unsafe {

components/script/dom/customelementregistry.rs

@@ -140,11 +140,10 @@ impl CustomElementRegistry {
         constructor: HandleObject,
         prototype: MutableHandleValue,
     ) -> ErrorResult {
-        let global_scope = self.window.upcast::<GlobalScope>();
         unsafe {
             // Step 10.1
             if !JS_GetProperty(
-                *global_scope.get_cx(),
+                *GlobalScope::get_cx(),
                 constructor,
                 b"prototype\0".as_ptr() as *const _,
                 prototype,
@@ -166,7 +165,7 @@ impl CustomElementRegistry {
     /// Steps 10.3, 10.4
     #[allow(unsafe_code)]
     unsafe fn get_callbacks(&self, prototype: HandleObject) -> Fallible<LifecycleCallbacks> {
-        let cx = self.window.get_cx();
+        let cx = GlobalScope::get_cx();
 
         // Step 4
         Ok(LifecycleCallbacks {
@@ -181,7 +180,7 @@ impl CustomElementRegistry {
     /// Step 10.6
     #[allow(unsafe_code)]
     fn get_observed_attributes(&self, constructor: HandleObject) -> Fallible<Vec<DOMString>> {
-        let cx = self.window.get_cx();
+        let cx = GlobalScope::get_cx();
         rooted!(in(*cx) let mut observed_attributes = UndefinedValue());
         if unsafe {
             !JS_GetProperty(
@@ -254,7 +253,7 @@ impl CustomElementRegistryMethods for CustomElementRegistry {
         constructor_: Rc<CustomElementConstructor>,
         options: &ElementDefinitionOptions,
     ) -> ErrorResult {
-        let cx = self.window.get_cx();
+        let cx = GlobalScope::get_cx();
         rooted!(in(*cx) let constructor = constructor_.callback());
         let name = LocalName::from(&*name);
 
@@ -429,7 +428,7 @@ impl CustomElementRegistryMethods for CustomElementRegistry {
 
         // Step 1
         if !is_valid_custom_element_name(&name) {
-            let promise = Promise::new_in_current_realm(&global_scope, comp);
+            let promise = Promise::new_in_current_realm(comp);
             promise.reject_native(&DOMException::new(&global_scope, DOMErrorName::SyntaxError));
             return promise;
         }
@@ -437,12 +436,12 @@ impl CustomElementRegistryMethods for CustomElementRegistry {
         // Step 2
         if let Some(definition) = self.definitions.borrow().get(&LocalName::from(&*name)) {
             unsafe {
-                let cx = global_scope.get_cx();
+                let cx = GlobalScope::get_cx();
                 rooted!(in(*cx) let mut constructor = UndefinedValue());
                 definition
                     .constructor
                     .to_jsval(*cx, constructor.handle_mut());
-                let promise = Promise::new_in_current_realm(&global_scope, comp);
+                let promise = Promise::new_in_current_realm(comp);
                 promise.resolve_native(&constructor.get());
                 return promise;
             }
@@ -453,7 +452,7 @@ impl CustomElementRegistryMethods for CustomElementRegistry {
 
         // Steps 4, 5
         let promise = map.get(&name).cloned().unwrap_or_else(|| {
-            let promise = Promise::new_in_current_realm(&global_scope, comp);
+            let promise = Promise::new_in_current_realm(comp);
             map.insert(name, promise.clone());
             promise
         });
@@ -543,7 +542,7 @@ impl CustomElementDefinition {
         prefix: Option<Prefix>,
     ) -> Fallible<DomRoot<Element>> {
         let window = document.window();
-        let cx = window.get_cx();
+        let cx = GlobalScope::get_cx();
         // Step 2
         rooted!(in(*cx) let constructor = ObjectValue(self.constructor.callback()));
         rooted!(in(*cx) let mut element = ptr::null_mut::<JSObject>());
@@ -662,7 +661,7 @@ pub fn upgrade_element(definition: Rc<CustomElementDefinition>, element: &Elemen
 
         // Step 8.exception.3
         let global = GlobalScope::current().expect("No current global");
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         unsafe {
             let ar = enter_realm(&*global);
             throw_dom_exception(cx, &global, error);
@@ -686,7 +685,7 @@ fn run_upgrade_constructor(
     element: &Element,
 ) -> ErrorResult {
     let window = window_from_node(element);
-    let cx = window.get_cx();
+    let cx = GlobalScope::get_cx();
     rooted!(in(*cx) let constructor_val = ObjectValue(constructor.callback()));
     rooted!(in(*cx) let mut element_val = UndefinedValue());
     unsafe {
@@ -909,7 +908,7 @@ impl CustomElementReactionStack {
                     return;
                 }
 
-                let cx = element.global().get_cx();
+                let cx = GlobalScope::get_cx();
                 // We might be here during HTML parsing, rather than
                 // during Javscript execution, and so we typically aren't
                 // already in a realm here.

components/script/dom/dissimilaroriginwindow.rs

@@ -46,7 +46,7 @@ pub struct DissimilarOriginWindow {
 impl DissimilarOriginWindow {
     #[allow(unsafe_code)]
     pub fn new(global_to_clone_from: &GlobalScope, window_proxy: &WindowProxy) -> DomRoot<Self> {
-        let cx = global_to_clone_from.get_cx();
+        let cx = GlobalScope::get_cx();
         let win = Box::new(Self {
             globalscope: GlobalScope::new_inherited(
                 PipelineId::new(),

components/script/dom/document.rs

@@ -3573,9 +3573,8 @@ impl Document {
     // https://fullscreen.spec.whatwg.org/#dom-element-requestfullscreen
     pub fn enter_fullscreen(&self, pending: &Element) -> Rc<Promise> {
         // Step 1
-        let in_realm_proof = AlreadyInRealm::assert(&self.global());
+        let in_realm_proof = AlreadyInRealm::assert();
-        let promise =
+        let promise = Promise::new_in_current_realm(InRealm::Already(&in_realm_proof));
-            Promise::new_in_current_realm(&self.global(), InRealm::Already(&in_realm_proof));
         let mut error = false;
 
         // Step 4
@@ -3642,8 +3641,8 @@ impl Document {
     pub fn exit_fullscreen(&self) -> Rc<Promise> {
         let global = self.global();
         // Step 1
-        let in_realm_proof = AlreadyInRealm::assert(&global);
+        let in_realm_proof = AlreadyInRealm::assert();
-        let promise = Promise::new_in_current_realm(&global, InRealm::Already(&in_realm_proof));
+        let promise = Promise::new_in_current_realm(InRealm::Already(&in_realm_proof));
         // Step 2
         if self.fullscreen_element.get().is_none() {
             promise.reject_error(Error::Type(String::from("fullscreen is null")));

components/script/dom/eventsource.rs

@@ -222,10 +222,10 @@ impl EventSourceContext {
         // Steps 4-5
         let event = {
             let _ac = enter_realm(&*event_source);
-            rooted!(in(*event_source.global().get_cx()) let mut data = UndefinedValue());
+            rooted!(in(*GlobalScope::get_cx()) let mut data = UndefinedValue());
             unsafe {
                 self.data
-                    .to_jsval(*event_source.global().get_cx(), data.handle_mut())
+                    .to_jsval(*GlobalScope::get_cx(), data.handle_mut())
             };
             MessageEvent::new(
                 &*event_source.global(),

components/script/dom/eventtarget.rs

@@ -184,7 +184,7 @@ impl CompiledEventListener {
                     CommonEventHandler::ErrorEventHandler(ref handler) => {
                         if let Some(event) = event.downcast::<ErrorEvent>() {
                             if object.is::<Window>() || object.is::<WorkerGlobalScope>() {
-                                let cx = object.global().get_cx();
+                                let cx = GlobalScope::get_cx();
                                 rooted!(in(*cx) let error = event.Error(cx));
                                 let return_value = handler.Call_(
                                     object,
@@ -242,7 +242,7 @@ impl CompiledEventListener {
 
                     CommonEventHandler::EventHandler(ref handler) => {
                         if let Ok(value) = handler.Call_(object, event, exception_handle) {
-                            let cx = object.global().get_cx();
+                            let cx = GlobalScope::get_cx();
                             rooted!(in(*cx) let value = value);
                             let value = value.handle();
 
@@ -525,7 +525,7 @@ impl EventTarget {
         let is_error = ty == &atom!("error") && self.is::<Window>();
         let args = if is_error { ERROR_ARG_NAMES } else { ARG_NAMES };
 
-        let cx = window.get_cx();
+        let cx = GlobalScope::get_cx();
         let options = unsafe {
             CompileOptionsWrapper::new(*cx, &handler.url.to_string(), handler.line as u32)
         };
@@ -592,7 +592,7 @@ impl EventTarget {
     where
         T: CallbackContainer,
     {
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
 
         let event_listener = listener.map(|listener| {
             InlineEventListener::Compiled(CommonEventHandler::EventHandler(unsafe {
@@ -607,7 +607,7 @@ impl EventTarget {
     where
         T: CallbackContainer,
     {
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
 
         let event_listener = listener.map(|listener| {
             InlineEventListener::Compiled(CommonEventHandler::ErrorEventHandler(unsafe {
@@ -625,7 +625,7 @@ impl EventTarget {
     ) where
         T: CallbackContainer,
     {
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
 
         let event_listener = listener.map(|listener| {
             InlineEventListener::Compiled(CommonEventHandler::BeforeUnloadEventHandler(unsafe {
@@ -637,7 +637,7 @@ impl EventTarget {
 
     #[allow(unsafe_code)]
     pub fn get_event_handler_common<T: CallbackContainer>(&self, ty: &str) -> Option<Rc<T>> {
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         let listener = self.get_inline_event_listener(&Atom::from(ty));
         unsafe {
             listener.map(|listener| {

components/script/dom/filereader.rs

@@ -258,7 +258,7 @@ impl FileReader {
                 let _ac = enter_realm(&*fr);
                 FileReader::perform_readasarraybuffer(
                     &fr.result,
-                    fr.global().get_cx(),
+                    GlobalScope::get_cx(),
                     data,
                     &blob_contents,
                 )

components/script/dom/globalscope.rs

@@ -1215,7 +1215,7 @@ impl GlobalScope {
                                     return;
                                 }
 
-                                rooted!(in(*global.get_cx()) let mut message = UndefinedValue());
+                                rooted!(in(*GlobalScope::get_cx()) let mut message = UndefinedValue());
 
                                 // Step 10.3 StructuredDeserialize(serialized, targetRealm).
                                 if let Ok(ports) = structuredclone::read(&global, data, message.handle_mut()) {
@@ -1269,7 +1269,7 @@ impl GlobalScope {
         };
         if let Some((dom_port, PortMessageTask { origin, data })) = should_dispatch {
             // Substep 3-4
-            rooted!(in(*self.get_cx()) let mut message_clone = UndefinedValue());
+            rooted!(in(*GlobalScope::get_cx()) let mut message_clone = UndefinedValue());
             if let Ok(ports) = structuredclone::read(self, data, message_clone.handle_mut()) {
                 // Substep 6
                 // Dispatch the event, using the dom message-port.
@@ -2120,7 +2120,7 @@ impl GlobalScope {
     /// Returns the global scope of the realm that the given DOM object's reflector
     /// was created in.
     #[allow(unsafe_code)]
-    pub fn from_reflector<T: DomObject>(reflector: &T) -> DomRoot<Self> {
+    pub fn from_reflector<T: DomObject>(reflector: &T, _realm: &AlreadyInRealm) -> DomRoot<Self> {
         unsafe { GlobalScope::from_object(*reflector.reflector().get_jsobject()) }
     }
 
@@ -2221,7 +2221,7 @@ impl GlobalScope {
     }
 
     #[allow(unsafe_code)]
-    pub fn get_cx(&self) -> SafeJSContext {
+    pub fn get_cx() -> SafeJSContext {
         unsafe { SafeJSContext::from_ptr(Runtime::get()) }
     }
 
@@ -2603,7 +2603,7 @@ impl GlobalScope {
             Some(metadata),
             self.time_profiler_chan().clone(),
             || {
-                let cx = self.get_cx();
+                let cx = GlobalScope::get_cx();
 
                 let ar = enter_realm(&*self);
 
@@ -2733,8 +2733,8 @@ impl GlobalScope {
         image: ImageBitmapSource,
         options: &ImageBitmapOptions,
     ) -> Rc<Promise> {
-        let in_realm_proof = AlreadyInRealm::assert(&self);
+        let in_realm_proof = AlreadyInRealm::assert();
-        let p = Promise::new_in_current_realm(&self, InRealm::Already(&in_realm_proof));
+        let p = Promise::new_in_current_realm(InRealm::Already(&in_realm_proof));
         if options.resizeWidth.map_or(false, |w| w == 0) {
             p.reject_error(Error::InvalidState);
             return p;
@@ -2857,7 +2857,7 @@ impl GlobalScope {
         // Only perform the checkpoint if we're not shutting down.
         if self.can_continue_running() {
             self.microtask_queue.checkpoint(
-                self.get_cx(),
+                GlobalScope::get_cx(),
                 |_| Some(DomRoot::from_ref(self)),
                 vec![DomRoot::from_ref(self)],
             );
@@ -2866,7 +2866,7 @@ impl GlobalScope {
 
     /// Enqueue a microtask for subsequent execution.
     pub fn enqueue_microtask(&self, job: Microtask) {
-        self.microtask_queue.enqueue(job, self.get_cx());
+        self.microtask_queue.enqueue(job, GlobalScope::get_cx());
     }
 
     /// Create a new sender/receiver pair that can be used to implement an on-demand

components/script/dom/gpu.rs

@@ -100,7 +100,7 @@ impl GPUMethods for GPU {
     // https://gpuweb.github.io/gpuweb/#dom-gpu-requestadapter
     fn RequestAdapter(&self, options: &GPURequestAdapterOptions, comp: InRealm) -> Rc<Promise> {
         let global = &self.global();
-        let promise = Promise::new_in_current_realm(global, comp);
+        let promise = Promise::new_in_current_realm(comp);
         let sender = response_async(&promise, self);
         let power_preference = match options.powerPreference {
             Some(GPUPowerPreference::Low_power) => PowerPreference::LowPower,

components/script/dom/gpuadapter.rs

@@ -78,7 +78,7 @@ impl GPUAdapterMethods for GPUAdapter {
 
     /// https://gpuweb.github.io/gpuweb/#dom-gpuadapter-requestdevice
     fn RequestDevice(&self, descriptor: &GPUDeviceDescriptor, comp: InRealm) -> Rc<Promise> {
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
         let sender = response_async(&promise, self);
         let mut features = wgt::Features::empty();
         for &ext in descriptor.extensions.iter() {

components/script/dom/gpubuffer.rs

@@ -6,7 +6,6 @@ use crate::dom::bindings::cell::DomRefCell;
 use crate::dom::bindings::codegen::Bindings::GPUBufferBinding::{GPUBufferMethods, GPUSize64};
 use crate::dom::bindings::codegen::Bindings::GPUMapModeBinding::GPUMapModeConstants;
 use crate::dom::bindings::error::{Error, Fallible};
-use crate::dom::bindings::reflector::DomObject;
 use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
 use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::bindings::str::USVString;
@@ -134,7 +133,7 @@ impl GPUBufferMethods for GPUBuffer {
     #[allow(unsafe_code)]
     /// https://gpuweb.github.io/gpuweb/#dom-gpubuffer-unmap
     fn Unmap(&self) {
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         // Step 1
         match self.state.get() {
             GPUBufferState::Unmapped | GPUBufferState::Destroyed => {
@@ -209,7 +208,7 @@ impl GPUBufferMethods for GPUBuffer {
         size: Option<GPUSize64>,
         comp: InRealm,
     ) -> Rc<Promise> {
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
         let range_size = if let Some(s) = size {
             s
         } else if offset >= self.size {

components/script/dom/gpudevice.rs

@@ -357,7 +357,7 @@ impl GPUDeviceMethods for GPUDevice {
 
     /// https://gpuweb.github.io/gpuweb/#dom-gpudevice-lost
     fn Lost(&self, comp: InRealm) -> Rc<Promise> {
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
         *self.lost_promise.borrow_mut() = Some(promise.clone());
         promise
     }
@@ -1117,7 +1117,7 @@ impl GPUDeviceMethods for GPUDevice {
     /// https://gpuweb.github.io/gpuweb/#dom-gpudevice-poperrorscope
     fn PopErrorScope(&self, comp: InRealm) -> Rc<Promise> {
         let mut context = self.scope_context.borrow_mut();
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
         let scope_id =
             if let Some(meta) = context.scope_stack.iter().rev().find(|m| !m.popped.get()) {
                 meta.popped.set(true);

components/script/dom/history.rs

@@ -117,7 +117,7 @@ impl History {
                     blobs: None,
                 };
                 let global_scope = self.window.upcast::<GlobalScope>();
-                rooted!(in(*global_scope.get_cx()) let mut state = UndefinedValue());
+                rooted!(in(*GlobalScope::get_cx()) let mut state = UndefinedValue());
                 if let Err(_) = structuredclone::read(&global_scope, data, state.handle_mut()) {
                     warn!("Error reading structuredclone data");
                 }

components/script/dom/htmlimageelement.rs

@@ -46,6 +46,7 @@ use crate::fetch::create_a_potential_cors_request;
 use crate::image_listener::{generate_cache_listener_for_element, ImageCacheListener};
 use crate::microtask::{Microtask, MicrotaskRunnable};
 use crate::network_listener::{self, NetworkListener, PreInvoke, ResourceTimingListener};
+use crate::realms::enter_realm;
 use crate::script_thread::ScriptThread;
 use crate::task_source::TaskSource;
 use app_units::{Au, AU_PER_PX};
@@ -56,6 +57,7 @@ use html5ever::{LocalName, Prefix, QualName};
 use ipc_channel::ipc;
 use ipc_channel::ipc::IpcSender;
 use ipc_channel::router::ROUTER;
+use js::jsapi::JSAutoRealm;
 use mime::{self, Mime};
 use msg::constellation_msg::PipelineId;
 use net_traits::image::base::{Image, ImageMetadata};
@@ -1353,6 +1355,13 @@ impl MicrotaskRunnable for ImageElementMicrotask {
             },
         }
     }
+
+    fn enter_realm(&self) -> JSAutoRealm {
+        match self {
+            &ImageElementMicrotask::StableStateUpdateImageDataTask { ref elem, .. } |
+            &ImageElementMicrotask::EnvironmentChangesTask { ref elem, .. } => enter_realm(&**elem),
+        }
+    }
 }
 
 pub trait LayoutHTMLImageElementHelpers {

components/script/dom/htmlinputelement.rs

@@ -833,7 +833,7 @@ impl HTMLInputElement {
         }
 
         // Rust's regex is not compatible, we need to use mozjs RegExp.
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         let _ac = enter_realm(self);
         rooted!(in(*cx) let mut pattern = ptr::null_mut::<JSObject>());
 

components/script/dom/htmlmediaelement.rs

@@ -62,7 +62,7 @@ use crate::dom::virtualmethods::VirtualMethods;
 use crate::fetch::{create_a_potential_cors_request, FetchCanceller};
 use crate::microtask::{Microtask, MicrotaskRunnable};
 use crate::network_listener::{self, NetworkListener, PreInvoke, ResourceTimingListener};
-use crate::realms::InRealm;
+use crate::realms::{enter_realm, InRealm};
 use crate::script_thread::ScriptThread;
 use crate::task_source::TaskSource;
 use dom_struct::dom_struct;
@@ -74,6 +74,7 @@ use html5ever::{LocalName, Prefix};
 use http::header::{self, HeaderMap, HeaderValue};
 use ipc_channel::ipc;
 use ipc_channel::router::ROUTER;
+use js::jsapi::JSAutoRealm;
 use media::{glplayer_channel, GLPlayerMsg, GLPlayerMsgForward, WindowGLContext};
 use net_traits::image::base::Image;
 use net_traits::request::Destination;
@@ -2112,7 +2113,7 @@ impl HTMLMediaElementMethods for HTMLMediaElement {
 
     // https://html.spec.whatwg.org/multipage/#dom-media-play
     fn Play(&self, comp: InRealm) -> Rc<Promise> {
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
         // Step 1.
         // FIXME(nox): Reject promise if not allowed to play.
 
@@ -2506,6 +2507,14 @@ impl MicrotaskRunnable for MediaElementMicrotask {
             },
         }
     }
+
+    fn enter_realm(&self) -> JSAutoRealm {
+        match self {
+            &MediaElementMicrotask::ResourceSelectionTask { ref elem, .. } |
+            &MediaElementMicrotask::PauseIfNotInDocumentTask { ref elem } |
+            &MediaElementMicrotask::SeekedTask { ref elem, .. } => enter_realm(&**elem),
+        }
+    }
 }
 
 enum Resource {

components/script/dom/htmlscriptelement.rs

@@ -110,7 +110,7 @@ unsafe extern "C" fn off_thread_compilation_callback(
         task!(off_thread_compile_continue: move || {
             let elem = script_element.root();
             let global = elem.global();
-            let cx = global.get_cx();
+            let cx = GlobalScope::get_cx();
             let _ar = enter_realm(&*global);
 
             let compiled_script = FinishOffThreadStencil(*cx, token.0, ptr::null_mut());
@@ -418,7 +418,7 @@ impl FetchResponseListener for ClassicContext {
 
         let elem = self.elem.root();
         let global = elem.global();
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         let _ar = enter_realm(&*global);
 
         let options = unsafe { CompileOptionsWrapper::new(*cx, final_url.as_str(), 1) };
@@ -1053,7 +1053,7 @@ impl HTMLScriptElement {
         } else {
             self.line_number as u32
         };
-        rooted!(in(*window.get_cx()) let mut rval = UndefinedValue());
+        rooted!(in(*GlobalScope::get_cx()) let mut rval = UndefinedValue());
         let global = window.upcast::<GlobalScope>();
         global.evaluate_script_on_global_with_result(
             &script.code,
@@ -1108,7 +1108,7 @@ impl HTMLScriptElement {
                 .map(|record| record.handle());
 
             if let Some(record) = record {
-                rooted!(in(*global.get_cx()) let mut rval = UndefinedValue());
+                rooted!(in(*GlobalScope::get_cx()) let mut rval = UndefinedValue());
                 let evaluated =
                     module_tree.execute_module(global, record, rval.handle_mut().into());
 

components/script/dom/imagedata.rs

@@ -39,7 +39,7 @@ impl ImageData {
     ) -> Fallible<DomRoot<ImageData>> {
         let len = width * height * 4;
         unsafe {
-            let cx = global.get_cx();
+            let cx = GlobalScope::get_cx();
             rooted!(in (*cx) let mut js_object = ptr::null_mut::<JSObject>());
             if let Some(ref mut d) = data {
                 d.resize(len as usize, 0);
@@ -60,7 +60,7 @@ impl ImageData {
         jsobject: *mut JSObject,
     ) -> Fallible<DomRoot<ImageData>> {
         // checking jsobject type
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         typedarray!(in(*cx) let array_res: Uint8ClampedArray = jsobject);
         let array = array_res.map_err(|_| {
             Error::Type("Argument to Image data is not an Uint8ClampedArray".to_owned())
@@ -111,7 +111,7 @@ impl ImageData {
         });
 
         let len = width * height * 4;
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
         Uint8ClampedArray::create(*cx, CreateWith::Length(len as usize), array.handle_mut())
             .unwrap();

components/script/dom/mediadevices.rs

@@ -44,7 +44,7 @@ impl MediaDevicesMethods for MediaDevices {
     /// https://w3c.github.io/mediacapture-main/#dom-mediadevices-getusermedia
     #[allow(unsafe_code)]
     fn GetUserMedia(&self, constraints: &MediaStreamConstraints, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         let media = ServoMedia::get().unwrap();
         let stream = MediaStream::new(&self.global());
         if let Some(constraints) = convert_constraints(&constraints.audio) {
@@ -67,9 +67,8 @@ impl MediaDevicesMethods for MediaDevices {
     /// https://w3c.github.io/mediacapture-main/#dom-mediadevices-enumeratedevices
     fn EnumerateDevices(&self) -> Rc<Promise> {
         // Step 1.
-        let global = self.global();
+        let in_realm_proof = AlreadyInRealm::assert();
-        let in_realm_proof = AlreadyInRealm::assert(&global);
+        let p = Promise::new_in_current_realm(InRealm::Already(&in_realm_proof));
-        let p = Promise::new_in_current_realm(&global, InRealm::Already(&in_realm_proof));
 
         // Step 2.
         // XXX These steps should be run in parallel.

components/script/dom/navigationpreloadmanager.rs

@@ -43,7 +43,7 @@ impl NavigationPreloadManager {
 impl NavigationPreloadManagerMethods for NavigationPreloadManager {
     // https://w3c.github.io/ServiceWorker/#navigation-preload-manager-enable
     fn Enable(&self, comp: InRealm) -> Rc<Promise> {
-        let promise = Promise::new_in_current_realm(&*self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
 
         // 2.
         if self.serviceworker_registration.is_active() {
@@ -65,7 +65,7 @@ impl NavigationPreloadManagerMethods for NavigationPreloadManager {
 
     // https://w3c.github.io/ServiceWorker/#navigation-preload-manager-disable
     fn Disable(&self, comp: InRealm) -> Rc<Promise> {
-        let promise = Promise::new_in_current_realm(&*self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
 
         // 2.
         if self.serviceworker_registration.is_active() {
@@ -87,7 +87,7 @@ impl NavigationPreloadManagerMethods for NavigationPreloadManager {
 
     // https://w3c.github.io/ServiceWorker/#navigation-preload-manager-setheadervalue
     fn SetHeaderValue(&self, value: ByteString, comp: InRealm) -> Rc<Promise> {
-        let promise = Promise::new_in_current_realm(&*self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
 
         // 2.
         if self.serviceworker_registration.is_active() {
@@ -109,7 +109,7 @@ impl NavigationPreloadManagerMethods for NavigationPreloadManager {
 
     // https://w3c.github.io/ServiceWorker/#navigation-preload-manager-getstate
     fn GetState(&self, comp: InRealm) -> Rc<Promise> {
-        let promise = Promise::new_in_current_realm(&*self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
         // 2.
         let mut state = NavigationPreloadState::empty();
 

components/script/dom/offlineaudiocontext.rs

@@ -121,7 +121,7 @@ impl OfflineAudioContextMethods for OfflineAudioContext {
 
     // https://webaudio.github.io/web-audio-api/#dom-offlineaudiocontext-startrendering
     fn StartRendering(&self, comp: InRealm) -> Rc<Promise> {
-        let promise = Promise::new_in_current_realm(&self.global(), comp);
+        let promise = Promise::new_in_current_realm(comp);
         if self.rendering_started.get() {
             promise.reject_error(Error::InvalidState);
             return promise;

components/script/dom/paintworkletglobalscope.rs

@@ -252,7 +252,7 @@ impl PaintWorkletGlobalScope {
             name, size_in_px.width, size_in_px.height, device_pixel_ratio
         );
 
-        let cx = self.worklet_global.get_cx();
+        let cx = WorkletGlobalScope::get_cx();
         let _ac = JSAutoRealm::new(*cx, self.worklet_global.reflector().get_jsobject().get());
 
         // TODO: Steps 1-2.1.
@@ -517,7 +517,7 @@ impl PaintWorkletGlobalScopeMethods for PaintWorkletGlobalScope {
     /// <https://drafts.css-houdini.org/css-paint-api/#dom-paintworkletglobalscope-registerpaint>
     fn RegisterPaint(&self, name: DOMString, paint_ctor: Rc<VoidFunction>) -> Fallible<()> {
         let name = Atom::from(name);
-        let cx = self.worklet_global.get_cx();
+        let cx = WorkletGlobalScope::get_cx();
         rooted!(in(*cx) let paint_obj = paint_ctor.callback_holder().get());
         rooted!(in(*cx) let paint_val = ObjectValue(paint_obj.get()));
 

components/script/dom/permissions.rs

@@ -87,8 +87,8 @@ impl Permissions {
         let p = match promise {
             Some(promise) => promise,
             None => {
-                let in_realm_proof = AlreadyInRealm::assert(&self.global());
+                let in_realm_proof = AlreadyInRealm::assert();
-                Promise::new_in_current_realm(&self.global(), InRealm::Already(&in_realm_proof))
+                Promise::new_in_current_realm(InRealm::Already(&in_realm_proof))
             },
         };
 

components/script/dom/promise.rs

@@ -88,11 +88,11 @@ impl Promise {
     pub fn new(global: &GlobalScope) -> Rc<Promise> {
         let realm = enter_realm(&*global);
         let comp = InRealm::Entered(&realm);
-        Promise::new_in_current_realm(global, comp)
+        Promise::new_in_current_realm(comp)
     }
 
-    pub fn new_in_current_realm(global: &GlobalScope, _comp: InRealm) -> Rc<Promise> {
+    pub fn new_in_current_realm(_comp: InRealm) -> Rc<Promise> {
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         rooted!(in(*cx) let mut obj = ptr::null_mut::<JSObject>());
         Promise::create_js_promise(cx, obj.handle_mut());
         Promise::new_with_js_promise(obj.handle(), cx)
@@ -100,7 +100,7 @@ impl Promise {
 
     #[allow(unsafe_code)]
     pub fn duplicate(&self) -> Rc<Promise> {
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         Promise::new_with_js_promise(self.reflector().get_jsobject(), cx)
     }
 
@@ -172,7 +172,7 @@ impl Promise {
     where
         T: ToJSValConvertible,
     {
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         let _ac = enter_realm(&*self);
         rooted!(in(*cx) let mut v = UndefinedValue());
         unsafe {
@@ -195,7 +195,7 @@ impl Promise {
     where
         T: ToJSValConvertible,
     {
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         let _ac = enter_realm(&*self);
         rooted!(in(*cx) let mut v = UndefinedValue());
         unsafe {
@@ -206,7 +206,7 @@ impl Promise {
 
     #[allow(unsafe_code)]
     pub fn reject_error(&self, error: Error) {
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         let _ac = enter_realm(&*self);
         rooted!(in(*cx) let mut v = UndefinedValue());
         unsafe {
@@ -245,7 +245,7 @@ impl Promise {
     #[allow(unsafe_code)]
     pub fn append_native_handler(&self, handler: &PromiseNativeHandler, _comp: InRealm) {
         let _ais = AutoEntryScript::new(&*handler.global());
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         rooted!(in(*cx) let resolve_func =
                 create_native_handler_function(*cx,
                                                handler.reflector().get_jsobject(),

components/script/dom/readablestream.rs

@@ -120,7 +120,7 @@ impl ReadableStream {
     ) -> DomRoot<ReadableStream> {
         let _ar = enter_realm(global);
         let _ais = AutoIncumbentScript::new(global);
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
 
         let source = Rc::new(ExternalUnderlyingSourceController::new(source));
 
@@ -157,7 +157,7 @@ impl ReadableStream {
     pub fn enqueue_native(&self, bytes: Vec<u8>) {
         let global = self.global();
         let _ar = enter_realm(&*global);
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
 
         let handle = unsafe { self.js_stream.handle() };
 
@@ -171,7 +171,7 @@ impl ReadableStream {
     pub fn error_native(&self, error: Error) {
         let global = self.global();
         let _ar = enter_realm(&*global);
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
 
         unsafe {
             rooted!(in(*cx) let mut js_error = UndefinedValue());
@@ -188,7 +188,7 @@ impl ReadableStream {
     pub fn close_native(&self) {
         let global = self.global();
         let _ar = enter_realm(&*global);
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
 
         let handle = unsafe { self.js_stream.handle() };
 
@@ -223,7 +223,7 @@ impl ReadableStream {
 
         let global = self.global();
         let _ar = enter_realm(&*global);
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
 
         unsafe {
             rooted!(in(*cx) let reader = ReadableStreamGetReader(
@@ -253,7 +253,7 @@ impl ReadableStream {
         let _ar = enter_realm(&*global);
         let _aes = AutoEntryScript::new(&*global);
 
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
 
         unsafe {
             rooted!(in(*cx) let promise_obj = ReadableStreamDefaultReaderRead(
@@ -276,7 +276,7 @@ impl ReadableStream {
 
         let global = self.global();
         let _ar = enter_realm(&*global);
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
 
         unsafe {
             ReadableStreamReaderReleaseLock(*cx, self.js_reader.handle());
@@ -293,7 +293,7 @@ impl ReadableStream {
         }
 
         // Otherwise, still double-check that script didn't lock the stream.
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         let mut locked_or_disturbed = false;
 
         unsafe {
@@ -306,7 +306,7 @@ impl ReadableStream {
     #[allow(unsafe_code)]
     pub fn is_disturbed(&self) -> bool {
         // Check that script didn't disturb the stream.
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         let mut locked_or_disturbed = false;
 
         unsafe {

components/script/dom/rtcdatachannel.rs

@@ -135,7 +135,7 @@ impl RTCDataChannel {
 
     pub fn on_error(&self, error: WebRtcError) {
         let global = self.global();
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         let _ac = JSAutoRealm::new(*cx, self.reflector().get_jsobject().get());
         let init = RTCErrorInit {
             errorDetail: RTCErrorDetailType::Data_channel_failure,
@@ -157,7 +157,7 @@ impl RTCDataChannel {
     pub fn on_message(&self, channel_message: DataChannelMessage) {
         unsafe {
             let global = self.global();
-            let cx = global.get_cx();
+            let cx = GlobalScope::get_cx();
             let _ac = JSAutoRealm::new(*cx, self.reflector().get_jsobject().get());
             rooted!(in(*cx) let mut message = UndefinedValue());
 

components/script/dom/rtcpeerconnection.rs

@@ -548,7 +548,7 @@ impl RTCPeerConnectionMethods for RTCPeerConnection {
 
     /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-addicecandidate
     fn AddIceCandidate(&self, candidate: &RTCIceCandidateInit, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         if candidate.sdpMid.is_none() && candidate.sdpMLineIndex.is_none() {
             p.reject_error(Error::Type(format!(
                 "one of sdpMid and sdpMLineIndex must be set"
@@ -583,7 +583,7 @@ impl RTCPeerConnectionMethods for RTCPeerConnection {
 
     /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-createoffer
     fn CreateOffer(&self, _options: &RTCOfferOptions, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         if self.closed.get() {
             p.reject_error(Error::InvalidState);
             return p;
@@ -595,7 +595,7 @@ impl RTCPeerConnectionMethods for RTCPeerConnection {
 
     /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-createoffer
     fn CreateAnswer(&self, _options: &RTCAnswerOptions, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         if self.closed.get() {
             p.reject_error(Error::InvalidState);
             return p;
@@ -618,7 +618,7 @@ impl RTCPeerConnectionMethods for RTCPeerConnection {
     /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-setlocaldescription
     fn SetLocalDescription(&self, desc: &RTCSessionDescriptionInit, comp: InRealm) -> Rc<Promise> {
         // XXXManishearth validate the current state
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         let this = Trusted::new(self);
         let desc: SessionDescription = desc.into();
         let trusted_promise = TrustedPromise::new(p.clone());
@@ -651,7 +651,7 @@ impl RTCPeerConnectionMethods for RTCPeerConnection {
     /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-setremotedescription
     fn SetRemoteDescription(&self, desc: &RTCSessionDescriptionInit, comp: InRealm) -> Rc<Promise> {
         // XXXManishearth validate the current state
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
         let this = Trusted::new(self);
         let desc: SessionDescription = desc.into();
         let trusted_promise = TrustedPromise::new(p.clone());

components/script/dom/serviceworkercontainer.rs

@@ -70,7 +70,7 @@ impl ServiceWorkerContainerMethods for ServiceWorkerContainer {
         let global = self.client.global();
 
         // A: Step 1
-        let promise = Promise::new_in_current_realm(&*global, comp);
+        let promise = Promise::new_in_current_realm(comp);
         let USVString(ref script_url) = script_url;
 
         // A: Step 3

components/script/dom/servoparser/mod.rs

@@ -34,6 +34,7 @@ use crate::dom::processinginstruction::ProcessingInstruction;
 use crate::dom::text::Text;
 use crate::dom::virtualmethods::vtable_for;
 use crate::network_listener::PreInvoke;
+use crate::realms::enter_realm;
 use crate::script_thread::ScriptThread;
 use content_security_policy::{self as csp, CspList};
 use dom_struct::dom_struct;
@@ -828,6 +829,8 @@ impl FetchResponseListener for ParserContext {
             return;
         }
 
+        let _realm = enter_realm(&*parser.document);
+
         parser.document.set_csp_list(csp_list);
         self.parser = Some(Trusted::new(&*parser));
         self.submit_resource_timing();
@@ -916,6 +919,7 @@ impl FetchResponseListener for ParserContext {
         if parser.aborted.get() {
             return;
         }
+        let _realm = enter_realm(&*parser);
         parser.parse_bytes_chunk(payload);
     }
 
@@ -931,6 +935,8 @@ impl FetchResponseListener for ParserContext {
             return;
         }
 
+        let _realm = enter_realm(&*parser);
+
         match status {
             // are we throwing this away or can we use it?
             Ok(_) => (),

components/script/dom/testbinding.rs

@@ -1005,7 +1005,7 @@ impl TestBindingMethods for TestBinding {
             resolve.map(SimpleHandler::new),
             reject.map(SimpleHandler::new),
         );
-        let p = Promise::new_in_current_realm(&global, comp.clone());
+        let p = Promise::new_in_current_realm(comp.clone());
         p.append_native_handler(&handler, comp);
         return p;
 
@@ -1028,7 +1028,7 @@ impl TestBindingMethods for TestBinding {
     }
 
     fn PromiseAttribute(&self, comp: InRealm) -> Rc<Promise> {
-        Promise::new_in_current_realm(&self.global(), comp)
+        Promise::new_in_current_realm(comp)
     }
 
     fn AcceptPromise(&self, _promise: &Promise) {}

components/script/dom/websocket.rs

@@ -554,9 +554,9 @@ impl TaskOnce for MessageReceivedTask {
 
         // Step 2-5.
         let global = ws.global();
-        // global.get_cx() returns a valid `JSContext` pointer, so this is safe.
+        // GlobalScope::get_cx() returns a valid `JSContext` pointer, so this is safe.
         unsafe {
-            let cx = global.get_cx();
+            let cx = GlobalScope::get_cx();
             let _ac = JSAutoRealm::new(*cx, ws.reflector().get_jsobject().get());
             rooted!(in(*cx) let mut message = UndefinedValue());
             match self.message {

components/script/dom/windowproxy.rs

@@ -165,7 +165,7 @@ impl WindowProxy {
             let WindowProxyHandler(handler) = window.windowproxy_handler();
             assert!(!handler.is_null());
 
-            let cx = window.get_cx();
+            let cx = GlobalScope::get_cx();
             let window_jsobject = window.reflector().get_jsobject();
             assert!(!window_jsobject.get().is_null());
             assert_ne!(
@@ -225,7 +225,7 @@ impl WindowProxy {
             let handler = CreateWrapperProxyHandler(&XORIGIN_PROXY_HANDLER);
             assert!(!handler.is_null());
 
-            let cx = global_to_clone_from.get_cx();
+            let cx = GlobalScope::get_cx();
 
             // Create a new browsing context.
             let window_proxy = Box::new(WindowProxy::new_inherited(
@@ -624,7 +624,7 @@ impl WindowProxy {
             let handler = CreateWrapperProxyHandler(traps);
             assert!(!handler.is_null());
 
-            let cx = window.get_cx();
+            let cx = GlobalScope::get_cx();
             let window_jsobject = window.reflector().get_jsobject();
             let old_js_proxy = self.reflector.get_jsobject();
             assert!(!window_jsobject.get().is_null());

components/script/dom/worker.rs

@@ -169,7 +169,7 @@ impl Worker {
         let global = worker.global();
         let target = worker.upcast();
         let _ac = enter_realm(target);
-        rooted!(in(*global.get_cx()) let mut message = UndefinedValue());
+        rooted!(in(*GlobalScope::get_cx()) let mut message = UndefinedValue());
         if let Ok(ports) = structuredclone::read(&global, data, message.handle_mut()) {
             MessageEvent::dispatch_jsval(target, &global, message.handle(), None, None, ports);
         } else {
@@ -247,7 +247,7 @@ impl WorkerMethods for Worker {
         self.terminated.set(true);
 
         // Step 3
-        let cx = self.global().get_cx();
+        let cx = GlobalScope::get_cx();
         unsafe { JS_RequestInterruptCallback(*cx) };
     }
 

components/script/dom/worklet.rs

@@ -130,8 +130,7 @@ impl WorkletMethods for Worklet {
         comp: InRealm,
     ) -> Rc<Promise> {
         // Step 1.
-        let global = self.window.upcast();
+        let promise = Promise::new_in_current_realm(comp);
-        let promise = Promise::new_in_current_realm(&global, comp);
 
         // Step 3.
         let module_url_record = match self.window.Document().base_url().join(&module_url.0) {

components/script/dom/workletglobalscope.rs

@@ -85,14 +85,14 @@ impl WorkletGlobalScope {
     }
 
     /// Get the JS context.
-    pub fn get_cx(&self) -> JSContext {
+    pub fn get_cx() -> JSContext {
-        self.globalscope.get_cx()
+        GlobalScope::get_cx()
     }
 
     /// Evaluate a JS script in this global.
     pub fn evaluate_js(&self, script: &str) -> bool {
         debug!("Evaluating Dom in a worklet.");
-        rooted!(in (*self.globalscope.get_cx()) let mut rval = UndefinedValue());
+        rooted!(in (*GlobalScope::get_cx()) let mut rval = UndefinedValue());
         self.globalscope.evaluate_js_on_global_with_result(
             &*script,
             rval.handle_mut(),

components/script/dom/xrinputsource.rs

@@ -57,7 +57,7 @@ impl XRInputSource {
         );
 
         let _ac = enter_realm(&*global);
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         unsafe {
             rooted!(in(*cx) let mut profiles = UndefinedValue());
             source.info.profiles.to_jsval(*cx, profiles.handle_mut());

components/script/dom/xrinputsourceschangeevent.rs

@@ -63,7 +63,7 @@ impl XRInputSourcesChangeEvent {
             event.init_event(type_, bubbles, cancelable);
         }
         let _ac = enter_realm(&*global);
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         unsafe {
             rooted!(in(*cx) let mut added_val = UndefinedValue());
             added.to_jsval(*cx, added_val.handle_mut());

components/script/dom/xrray.rs

@@ -116,7 +116,7 @@ impl XRRayMethods for XRRay {
         // https://immersive-web.github.io/hit-test/#xrray-obtain-the-matrix
         // Step 1
         if self.matrix.get().is_null() {
-            let cx = self.global().get_cx();
+            let cx = GlobalScope::get_cx();
             // Step 2
             let z = Vector3D::new(0., 0., -1.);
             // Step 3

components/script/dom/xrrigidtransform.rs

@@ -117,7 +117,7 @@ impl XRRigidTransformMethods for XRRigidTransform {
     // https://immersive-web.github.io/webxr/#dom-xrrigidtransform-matrix
     fn Matrix(&self, _cx: JSContext) -> NonNull<JSObject> {
         if self.matrix.get().is_null() {
-            let cx = self.global().get_cx();
+            let cx = GlobalScope::get_cx();
             // According to the spec all matrices are column-major,
             // however euclid uses row vectors so we use .to_array()
             let arr = self.transform.to_transform().to_array();

components/script/dom/xrsession.rs

@@ -757,7 +757,7 @@ impl XRSessionMethods for XRSession {
 
     /// https://immersive-web.github.io/webxr/#dom-xrsession-requestreferencespace
     fn RequestReferenceSpace(&self, ty: XRReferenceSpaceType, comp: InRealm) -> Rc<Promise> {
-        let p = Promise::new_in_current_realm(&self.global(), comp);
+        let p = Promise::new_in_current_realm(comp);
 
         // https://immersive-web.github.io/webxr/#create-a-reference-space
 

components/script/dom/xrsystem.rs

@@ -14,6 +14,7 @@ use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
 use crate::dom::bindings::trace::RootedTraceableBox;
 use crate::dom::eventtarget::EventTarget;
 use crate::dom::gamepad::Gamepad;
+use crate::dom::globalscope::GlobalScope;
 use crate::dom::promise::Promise;
 use crate::dom::window::Window;
 use crate::dom::xrsession::XRSession;
@@ -158,7 +159,7 @@ impl XRSystemMethods for XRSystem {
     ) -> Rc<Promise> {
         let global = self.global();
         let window = global.as_window();
-        let promise = Promise::new_in_current_realm(&global, comp);
+        let promise = Promise::new_in_current_realm(comp);
 
         if mode != XRSessionMode::Inline {
             if !ScriptThread::is_user_interacting() {
@@ -180,7 +181,7 @@ impl XRSystemMethods for XRSystem {
 
         let mut required_features = vec![];
         let mut optional_features = vec![];
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
 
         // We are supposed to include "viewer" and on immersive devices "local"
         // by default here, but this is handled directly in requestReferenceSpace()

components/script/dom/xrview.rs

@@ -3,7 +3,6 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use crate::dom::bindings::codegen::Bindings::XRViewBinding::{XREye, XRViewMethods};
-use crate::dom::bindings::reflector::DomObject;
 use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
 use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::bindings::utils::create_typed_array;
@@ -90,7 +89,7 @@ impl XRViewMethods for XRView {
     /// https://immersive-web.github.io/webxr/#dom-xrview-projectionmatrix
     fn ProjectionMatrix(&self, _cx: JSContext) -> NonNull<JSObject> {
         if self.proj.get().is_null() {
-            let cx = self.global().get_cx();
+            let cx = GlobalScope::get_cx();
             // row_major since euclid uses row vectors
             let proj = self.view.projection.to_array();
             create_typed_array(cx, &proj, &self.proj);

components/script/dom/xrviewerpose.rs

@@ -154,7 +154,7 @@ impl XRViewerPose {
         let transform = XRRigidTransform::new(global, cast_transform(transform));
         let pose = reflect_dom_object(Box::new(XRViewerPose::new_inherited(&transform)), global);
 
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         unsafe {
             rooted!(in(*cx) let mut jsval = UndefinedValue());
             views.to_jsval(*cx, jsval.handle_mut());

components/script/fetch.rs

@@ -142,7 +142,7 @@ pub fn Fetch(
     let core_resource_thread = global.core_resource_thread();
 
     // Step 1
-    let promise = Promise::new_in_current_realm(global, comp);
+    let promise = Promise::new_in_current_realm(comp);
     let response = Response::new(global);
 
     // Step 2

components/script/microtask.rs

@@ -15,9 +15,10 @@ use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmlimageelement::ImageElementMicrotask;
 use crate::dom::htmlmediaelement::MediaElementMicrotask;
 use crate::dom::mutationobserver::MutationObserver;
+use crate::realms::enter_realm;
 use crate::script_runtime::{notify_about_rejected_promises, JSContext};
 use crate::script_thread::ScriptThread;
-use js::jsapi::{JobQueueIsEmpty, JobQueueMayNotBeEmpty};
+use js::jsapi::{JSAutoRealm, JobQueueIsEmpty, JobQueueMayNotBeEmpty};
 use msg::constellation_msg::PipelineId;
 use std::cell::Cell;
 use std::mem;
@@ -44,6 +45,7 @@ pub enum Microtask {
 
 pub trait MicrotaskRunnable {
     fn handler(&self) {}
+    fn enter_realm(&self) -> JSAutoRealm;
 }
 
 /// A promise callback scheduled to run during the next microtask checkpoint (#4283).
@@ -108,19 +110,23 @@ impl MicrotaskQueue {
                         if let Some(target) = target_provider(job.pipeline) {
                             let was_interacting = ScriptThread::is_user_interacting();
                             ScriptThread::set_user_interacting(job.is_user_interacting);
+                            let _realm = enter_realm(&*target);
                             let _ = job.callback.Call_(&*target, ExceptionHandling::Report);
                             ScriptThread::set_user_interacting(was_interacting);
                         }
                     },
                     Microtask::User(ref job) => {
                         if let Some(target) = target_provider(job.pipeline) {
+                            let _realm = enter_realm(&*target);
                             let _ = job.callback.Call_(&*target, ExceptionHandling::Report);
                         }
                     },
                     Microtask::MediaElement(ref task) => {
+                        let _realm = task.enter_realm();
                         task.handler();
                     },
                     Microtask::ImageElement(ref task) => {
+                        let _realm = task.enter_realm();
                         task.handler();
                     },
                     Microtask::CustomElementReaction => {

components/script/realms.rs

@@ -11,9 +11,9 @@ pub struct AlreadyInRealm(());
 
 impl AlreadyInRealm {
     #![allow(unsafe_code)]
-    pub fn assert(global: &GlobalScope) -> AlreadyInRealm {
+    pub fn assert() -> AlreadyInRealm {
         unsafe {
-            assert!(!GetCurrentRealmOrNull(*global.get_cx()).is_null());
+            assert!(!GetCurrentRealmOrNull(*GlobalScope::get_cx()).is_null());
         }
         AlreadyInRealm(())
     }
@@ -44,7 +44,7 @@ impl<'a> InRealm<'a> {
 
 pub fn enter_realm(object: &impl DomObject) -> JSAutoRealm {
     JSAutoRealm::new(
-        *object.global().get_cx(),
+        *GlobalScope::get_cx(),
         object.reflector().get_jsobject().get(),
     )
 }

components/script/script_module.rs

@@ -81,8 +81,8 @@ use uuid::Uuid;
 
 #[allow(unsafe_code)]
 unsafe fn gen_type_error(global: &GlobalScope, string: String) -> RethrowError {
-    rooted!(in(*global.get_cx()) let mut thrown = UndefinedValue());
+    rooted!(in(*GlobalScope::get_cx()) let mut thrown = UndefinedValue());
-    Error::Type(string).to_jsval(*global.get_cx(), &global, thrown.handle_mut());
+    Error::Type(string).to_jsval(*GlobalScope::get_cx(), &global, thrown.handle_mut());
 
     return RethrowError(RootedTraceableBox::from_box(Heap::boxed(thrown.get())));
 }
@@ -357,7 +357,7 @@ impl ModuleTree {
         match promise.as_ref() {
             Some(promise) => promise.append_native_handler(&handler, comp),
             None => {
-                let new_promise = Promise::new_in_current_realm(&owner.global(), comp);
+                let new_promise = Promise::new_in_current_realm(comp);
                 new_promise.append_native_handler(&handler, comp);
                 *promise = Some(new_promise);
             },
@@ -393,7 +393,7 @@ impl ModuleTree {
         match promise.as_ref() {
             Some(promise) => promise.append_native_handler(&handler, comp),
             None => {
-                let new_promise = Promise::new_in_current_realm(&owner.global(), comp);
+                let new_promise = Promise::new_in_current_realm(comp);
                 new_promise.append_native_handler(&handler, comp);
                 *promise = Some(new_promise);
             },
@@ -421,14 +421,14 @@ impl ModuleTree {
         url: ServoUrl,
         options: ScriptFetchOptions,
     ) -> Result<ModuleObject, RethrowError> {
-        let _ac = JSAutoRealm::new(*global.get_cx(), *global.reflector().get_jsobject());
+        let cx = GlobalScope::get_cx();
+        let _ac = JSAutoRealm::new(*cx, *global.reflector().get_jsobject());
 
-        let compile_options =
+        let compile_options = unsafe { CompileOptionsWrapper::new(*cx, url.as_str(), 1) };
-            unsafe { CompileOptionsWrapper::new(*global.get_cx(), url.as_str(), 1) };
 
         unsafe {
-            rooted!(in(*global.get_cx()) let mut module_script = CompileModule1(
+            rooted!(in(*cx) let mut module_script = CompileModule1(
-                *global.get_cx(),
+                *cx,
                 compile_options.ptr,
                 &mut transform_str_to_source_text(&module_script_text),
             ));
@@ -436,12 +436,9 @@ impl ModuleTree {
             if module_script.is_null() {
                 warn!("fail to compile module script of {}", url);
 
-                rooted!(in(*global.get_cx()) let mut exception = UndefinedValue());
+                rooted!(in(*cx) let mut exception = UndefinedValue());
-                assert!(JS_GetPendingException(
+                assert!(JS_GetPendingException(*cx, &mut exception.handle_mut()));
-                    *global.get_cx(),
+                JS_ClearPendingException(*cx);
-                    &mut exception.handle_mut()
-                ));
-                JS_ClearPendingException(*global.get_cx());
 
                 return Err(RethrowError(RootedTraceableBox::from_box(Heap::boxed(
                     exception.get(),
@@ -474,18 +471,16 @@ impl ModuleTree {
         global: &GlobalScope,
         module_record: HandleObject,
     ) -> Result<(), RethrowError> {
-        let _ac = JSAutoRealm::new(*global.get_cx(), *global.reflector().get_jsobject());
+        let cx = GlobalScope::get_cx();
+        let _ac = JSAutoRealm::new(*cx, *global.reflector().get_jsobject());
 
         unsafe {
-            if !ModuleLink(*global.get_cx(), module_record) {
+            if !ModuleLink(*cx, module_record) {
                 warn!("fail to link & instantiate module");
 
-                rooted!(in(*global.get_cx()) let mut exception = UndefinedValue());
+                rooted!(in(*cx) let mut exception = UndefinedValue());
-                assert!(JS_GetPendingException(
+                assert!(JS_GetPendingException(*cx, &mut exception.handle_mut()));
-                    *global.get_cx(),
+                JS_ClearPendingException(*cx);
-                    &mut exception.handle_mut()
-                ));
-                JS_ClearPendingException(*global.get_cx());
 
                 Err(RethrowError(RootedTraceableBox::from_box(Heap::boxed(
                     exception.get(),
@@ -505,7 +500,7 @@ impl ModuleTree {
         module_record: HandleObject,
         eval_result: MutableHandleValue,
     ) -> Result<(), RethrowError> {
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         let _ac = JSAutoRealm::new(*cx, *global.reflector().get_jsobject());
 
         unsafe {
@@ -547,11 +542,11 @@ impl ModuleTree {
             unsafe {
                 let ar = enter_realm(&*global);
                 JS_SetPendingException(
-                    *global.get_cx(),
+                    *GlobalScope::get_cx(),
                     exception.handle(),
                     ExceptionStackBehavior::Capture,
                 );
-                report_pending_exception(*global.get_cx(), true, InRealm::Entered(&ar));
+                report_pending_exception(*GlobalScope::get_cx(), true, InRealm::Entered(&ar));
             }
         }
     }
@@ -563,16 +558,17 @@ impl ModuleTree {
         module_object: HandleObject,
         base_url: ServoUrl,
     ) -> Result<IndexSet<ServoUrl>, RethrowError> {
-        let _ac = JSAutoRealm::new(*global.get_cx(), *global.reflector().get_jsobject());
+        let cx = GlobalScope::get_cx();
+        let _ac = JSAutoRealm::new(*cx, *global.reflector().get_jsobject());
 
         let mut specifier_urls = IndexSet::new();
 
         unsafe {
-            rooted!(in(*global.get_cx()) let requested_modules = GetRequestedModules(*global.get_cx(), module_object));
+            rooted!(in(*cx) let requested_modules = GetRequestedModules(*cx, module_object));
 
             let mut length = 0;
 
-            if !GetArrayLength(*global.get_cx(), requested_modules.handle(), &mut length) {
+            if !GetArrayLength(*cx, requested_modules.handle(), &mut length) {
                 let module_length_error =
                     gen_type_error(&global, "Wrong length of requested modules".to_owned());
 
@@ -580,10 +576,10 @@ impl ModuleTree {
             }
 
             for index in 0..length {
-                rooted!(in(*global.get_cx()) let mut element = UndefinedValue());
+                rooted!(in(*cx) let mut element = UndefinedValue());
 
                 if !JS_GetElement(
-                    *global.get_cx(),
+                    *cx,
                     requested_modules.handle(),
                     index,
                     &mut element.handle_mut(),
@@ -594,12 +590,12 @@ impl ModuleTree {
                     return Err(get_element_error);
                 }
 
-                rooted!(in(*global.get_cx()) let specifier = GetRequestedModuleSpecifier(
+                rooted!(in(*cx) let specifier = GetRequestedModuleSpecifier(
-                    *global.get_cx(), element.handle()
+                    *cx, element.handle()
                 ));
 
                 let url = ModuleTree::resolve_module_specifier(
-                    *global.get_cx(),
+                    *cx,
                     &base_url,
                     specifier.handle().into_handle(),
                 );
@@ -976,7 +972,7 @@ impl ModuleOwner {
 
         let module = global.dynamic_module_list().remove(dynamic_module_id);
 
-        let cx = global.get_cx();
+        let cx = GlobalScope::get_cx();
         let module_tree = module_identity.get_module_tree(&global);
 
         // In the timing of executing this `finish_dynamic_module` function,
@@ -986,7 +982,7 @@ impl ModuleOwner {
         let network_error = module_tree.get_network_error().borrow().as_ref().cloned();
         let existing_rethrow_error = module_tree.get_rethrow_error().borrow().as_ref().cloned();
 
-        rooted!(in(*global.get_cx()) let mut rval = UndefinedValue());
+        rooted!(in(*cx) let mut rval = UndefinedValue());
         if network_error.is_none() && existing_rethrow_error.is_none() {
             let record = module_tree
                 .get_record()
@@ -1355,7 +1351,7 @@ fn fetch_an_import_module_script_graph(
     promise: Rc<Promise>,
 ) -> Result<(), RethrowError> {
     // Step 1.
-    let cx = global.get_cx();
+    let cx = GlobalScope::get_cx();
     rooted!(in(*cx) let specifier = unsafe { GetModuleRequestSpecifier(*cx, module_request) });
     let url = ModuleTree::resolve_module_specifier(*cx, &base_url, specifier.handle().into());
 
@@ -1428,9 +1424,9 @@ unsafe extern "C" fn HostResolveImportedModule(
     }
 
     // Step 5.
-    rooted!(in(*global_scope.get_cx()) let specifier = GetModuleRequestSpecifier(cx, specifier));
+    rooted!(in(*GlobalScope::get_cx()) let specifier = GetModuleRequestSpecifier(cx, specifier));
     let url = ModuleTree::resolve_module_specifier(
-        *global_scope.get_cx(),
+        *GlobalScope::get_cx(),
         &base_url,
         specifier.handle().into(),
     );

components/script/script_runtime.rs

@@ -297,7 +297,7 @@ unsafe extern "C" fn promise_rejection_tracker(
                 global.dom_manipulation_task_source().queue(
                 task!(rejection_handled_event: move || {
                     let target = target.root();
-                    let cx = target.global().get_cx();
+                    let cx = GlobalScope::get_cx();
                     let root_promise = trusted_promise.root();
 
                     rooted!(in(*cx) let mut reason = UndefinedValue());
@@ -324,7 +324,7 @@ unsafe extern "C" fn promise_rejection_tracker(
 #[allow(unsafe_code, unrooted_must_root)]
 /// https://html.spec.whatwg.org/multipage/#notify-about-rejected-promises
 pub fn notify_about_rejected_promises(global: &GlobalScope) {
-    let cx = global.get_cx();
+    let cx = GlobalScope::get_cx();
     unsafe {
         // Step 2.
         if global.get_uncaught_rejections().borrow().len() > 0 {
@@ -350,7 +350,7 @@ pub fn notify_about_rejected_promises(global: &GlobalScope) {
             global.dom_manipulation_task_source().queue(
                 task!(unhandled_rejection_event: move || {
                     let target = target.root();
-                    let cx = target.global().get_cx();
+                    let cx = GlobalScope::get_cx();
 
                     for promise in uncaught_rejections {
                         let promise = promise.root();

components/script/script_thread.rs

@@ -1473,6 +1473,12 @@ impl ScriptThread {
         let mut mouse_move_event_index = None;
         let mut animation_ticks = HashSet::new();
         loop {
+            let pipeline_id = self.message_to_pipeline(&event);
+            let _realm = pipeline_id.map(|id| {
+                let global = self.documents.borrow().find_global(id);
+                global.map(|global| enter_realm(&*global))
+            });
+
             // https://html.spec.whatwg.org/multipage/#event-loop-processing-model step 7
             match event {
                 // This has to be handled before the ResizeMsg below,
@@ -1592,6 +1598,11 @@ impl ScriptThread {
             let category = self.categorize_msg(&msg);
             let pipeline_id = self.message_to_pipeline(&msg);
 
+            let _realm = pipeline_id.and_then(|id| {
+                let global = self.documents.borrow().find_global(id);
+                global.map(|global| enter_realm(&*global))
+            });
+
             if self.closing.load(Ordering::SeqCst) {
                 // If we've received the closed signal from the BHM, only handle exit messages.
                 match msg {
@@ -1638,6 +1649,7 @@ impl ScriptThread {
             // https://html.spec.whatwg.org/multipage/#the-end step 6
             let mut docs = self.docs_with_no_blocking_loads.borrow_mut();
             for document in docs.iter() {
+                let _realm = enter_realm(&**document);
                 document.maybe_queue_document_completion();
             }
             docs.clear();
@@ -1656,6 +1668,8 @@ impl ScriptThread {
             }
             let window = document.window();
 
+            let _realm = enter_realm(&*document);
+
             window
                 .upcast::<GlobalScope>()
                 .perform_a_dom_garbage_collection_checkpoint();
@@ -1684,6 +1698,7 @@ impl ScriptThread {
         }
 
         for (_, document) in self.documents.borrow().iter() {
+            let _realm = enter_realm(&*document);
             document.animations().send_pending_events(document.window());
         }
     }
@@ -1756,7 +1771,9 @@ impl ScriptThread {
             MixedMessage::FromConstellation(ref inner_msg) => match *inner_msg {
                 StopDelayingLoadEventsMode(id) => Some(id),
                 NavigationResponse(id, _) => Some(id),
-                AttachLayout(ref new_layout_info) => Some(new_layout_info.new_pipeline_id),
+                AttachLayout(ref new_layout_info) => new_layout_info
+                    .parent_info
+                    .or(Some(new_layout_info.new_pipeline_id)),
                 Resize(id, ..) => Some(id),
                 ResizeInactive(id, ..) => Some(id),
                 UnloadDocument(id) => Some(id),
@@ -1786,7 +1803,7 @@ impl ScriptThread {
                 DispatchStorageEvent(id, ..) => Some(id),
                 ReportCSSError(id, ..) => Some(id),
                 Reload(id, ..) => Some(id),
-                PaintMetric(..) => None,
+                PaintMetric(id, ..) => Some(id),
                 ExitFullScreen(id, ..) => Some(id),
                 MediaSessionAction(..) => None,
                 SetWebGPUPort(..) => None,
@@ -2070,7 +2087,13 @@ impl ScriptThread {
 
     fn handle_msg_from_script(&self, msg: MainThreadScriptMsg) {
         match msg {
-            MainThreadScriptMsg::Common(CommonScriptMsg::Task(_, task, _, _)) => task.run_box(),
+            MainThreadScriptMsg::Common(CommonScriptMsg::Task(_, task, pipeline_id, _)) => {
+                let _realm = pipeline_id.and_then(|id| {
+                    let global = self.documents.borrow().find_global(id);
+                    global.map(|global| enter_realm(&*global))
+                });
+                task.run_box()
+            },
             MainThreadScriptMsg::Common(CommonScriptMsg::CollectReports(chan)) => {
                 self.collect_reports(chan)
             },
@@ -3277,6 +3300,8 @@ impl ScriptThread {
             incomplete.inherited_secure_context,
         );
 
+        let _realm = enter_realm(&*window);
+
         // Initialize the browsing context for the window.
         let window_proxy = self.local_window_proxy(
             &window,
@@ -3460,6 +3485,8 @@ impl ScriptThread {
             );
         }
 
+        let _realm = enter_realm(&*window);
+
         // Assuming all CompositionEvent are generated by user interactions.
         ScriptThread::set_user_interacting(true);
         match event {
@@ -3697,7 +3724,7 @@ impl ScriptThread {
 
         // Script source is ready to be evaluated (11.)
         let _ac = enter_realm(global_scope);
-        rooted!(in(*global_scope.get_cx()) let mut jsval = UndefinedValue());
+        rooted!(in(*GlobalScope::get_cx()) let mut jsval = UndefinedValue());
         global_scope.evaluate_js_on_global_with_result(
             &script_source,
             jsval.handle_mut(),
@@ -3708,7 +3735,7 @@ impl ScriptThread {
         load_data.js_eval_result = if jsval.get().is_string() {
             unsafe {
                 let strval = DOMString::from_jsval(
-                    *global_scope.get_cx(),
+                    *GlobalScope::get_cx(),
                     jsval.handle(),
                     StringificationBehavior::Empty,
                 );
@@ -3978,7 +4005,7 @@ impl ScriptThread {
                 .documents
                 .borrow()
                 .iter()
-                .map(|(_id, document)| document.global())
+                .map(|(_id, document)| DomRoot::from_ref(document.window().upcast()))
                 .collect();
 
             self.microtask_queue.checkpoint(

components/script/timers.rs

@@ -540,7 +540,7 @@ impl JsTimerTask {
         match self.callback {
             InternalTimerCallback::StringTimerCallback(ref code_str) => {
                 let global = this.global();
-                let cx = global.get_cx();
+                let cx = GlobalScope::get_cx();
                 rooted!(in(*cx) let mut rval = UndefinedValue());
                 // FIXME(cybai): Use base url properly by saving private reference for timers (#27260)
                 global.evaluate_js_on_global_with_result(