Modify *::get_cx methods to return a safe JSContext instead of a raw one

43 files changed, 306 insertions, 321 deletions

diff --git a/components/script/body.rs b/components/script/body.rs
index 1e18bc565a6..728315bf1fa 100644
--- a/components/script/body.rs
+++ b/components/script/body.rs
@@ -13,8 +13,8 @@ use crate::dom::blob::{Blob, BlobImpl};
 use crate::dom::formdata::FormData;
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::promise::Promise;
+use crate::script_runtime::JSContext;
 use js::jsapi::Heap;
-use js::jsapi::JSContext;
 use js::jsapi::JSObject;
 use js::jsapi::JS_ClearPendingException;
 use js::jsapi::Value as JSValue;
@@ -122,7 +122,7 @@ fn run_package_data_algorithm<T: BodyOperations + DomObject>(
         BodyType::Json => run_json_data_algorithm(cx, bytes),
         BodyType::Blob => run_blob_data_algorithm(&global, bytes, mime),
         BodyType::FormData => run_form_data_algorithm(&global, bytes, mime),
-        BodyType::ArrayBuffer => unsafe { run_array_buffer_data_algorithm(cx, bytes) },
+        BodyType::ArrayBuffer => run_array_buffer_data_algorithm(cx, bytes),
     }
 }
 
@@ -133,20 +133,20 @@ fn run_text_data_algorithm(bytes: Vec<u8>) -> Fallible<FetchedData> {
 }
 
 #[allow(unsafe_code)]
-fn run_json_data_algorithm(cx: *mut JSContext, bytes: Vec<u8>) -> Fallible<FetchedData> {
+fn run_json_data_algorithm(cx: JSContext, bytes: Vec<u8>) -> Fallible<FetchedData> {
     let json_text = String::from_utf8_lossy(&bytes);
     let json_text: Vec<u16> = json_text.encode_utf16().collect();
-    rooted!(in(cx) let mut rval = UndefinedValue());
+    rooted!(in(*cx) let mut rval = UndefinedValue());
     unsafe {
         if !JS_ParseJSON(
-            cx,
+            *cx,
             json_text.as_ptr(),
             json_text.len() as u32,
             rval.handle_mut(),
         ) {
-            rooted!(in(cx) let mut exception = UndefinedValue());
-            assert!(JS_GetPendingException(cx, exception.handle_mut()));
-            JS_ClearPendingException(cx);
+            rooted!(in(*cx) let mut exception = UndefinedValue());
+            assert!(JS_GetPendingException(*cx, exception.handle_mut()));
+            JS_ClearPendingException(*cx);
             return Ok(FetchedData::JSException(RootedTraceableBox::from_box(
                 Heap::boxed(exception.get()),
             )));
@@ -200,13 +200,15 @@ fn run_form_data_algorithm(
 }
 
 #[allow(unsafe_code)]
-unsafe fn run_array_buffer_data_algorithm(
-    cx: *mut JSContext,
-    bytes: Vec<u8>,
-) -> Fallible<FetchedData> {
-    rooted!(in(cx) let mut array_buffer_ptr = ptr::null_mut::<JSObject>());
-    let arraybuffer =
-        ArrayBuffer::create(cx, CreateWith::Slice(&bytes), array_buffer_ptr.handle_mut());
+fn run_array_buffer_data_algorithm(cx: JSContext, bytes: Vec<u8>) -> Fallible<FetchedData> {
+    rooted!(in(*cx) let mut array_buffer_ptr = ptr::null_mut::<JSObject>());
+    let arraybuffer = unsafe {
+        ArrayBuffer::create(
+            *cx,
+            CreateWith::Slice(&bytes),
+            array_buffer_ptr.handle_mut(),
+        )
+    };
     if arraybuffer.is_err() {
         return Err(Error::JSFailed);
     }
diff --git a/components/script/compartments.rs b/components/script/compartments.rs
index cb8c973e70e..c26e72ccd1a 100644
--- a/components/script/compartments.rs
+++ b/components/script/compartments.rs
@@ -12,7 +12,7 @@ impl AlreadyInCompartment {
     #![allow(unsafe_code)]
     pub fn assert(global: &GlobalScope) -> AlreadyInCompartment {
         unsafe {
-            assert!(!GetCurrentRealmOrNull(global.get_cx()).is_null());
+            assert!(!GetCurrentRealmOrNull(*global.get_cx()).is_null());
         }
         AlreadyInCompartment(())
     }
@@ -43,7 +43,7 @@ impl<'a> InCompartment<'a> {
 
 pub fn enter_realm(object: &impl DomObject) -> JSAutoRealm {
     JSAutoRealm::new(
-        object.global().get_cx(),
+        *object.global().get_cx(),
         object.reflector().get_jsobject().get(),
     )
 }
diff --git a/components/script/devtools.rs b/components/script/devtools.rs
index 5a0e1c9090c..7ae02dd3e1f 100644
--- a/components/script/devtools.rs
+++ b/components/script/devtools.rs
@@ -36,7 +36,7 @@ pub fn handle_evaluate_js(global: &GlobalScope, eval: String, reply: IpcSender<E
     let result = unsafe {
         let cx = global.get_cx();
         let _ac = enter_realm(global);
-        rooted!(in(cx) let mut rval = UndefinedValue());
+        rooted!(in(*cx) let mut rval = UndefinedValue());
         global.evaluate_js_on_global_with_result(&eval, rval.handle_mut());
 
         if rval.is_undefined() {
@@ -45,20 +45,20 @@ pub fn handle_evaluate_js(global: &GlobalScope, eval: String, reply: IpcSender<E
             EvaluateJSReply::BooleanValue(rval.to_boolean())
         } else if rval.is_double() || rval.is_int32() {
             EvaluateJSReply::NumberValue(
-                match FromJSValConvertible::from_jsval(cx, rval.handle(), ()) {
+                match FromJSValConvertible::from_jsval(*cx, rval.handle(), ()) {
                     Ok(ConversionResult::Success(v)) => v,
                     _ => unreachable!(),
                 },
             )
         } else if rval.is_string() {
-            EvaluateJSReply::StringValue(String::from(jsstring_to_str(cx, rval.to_string())))
+            EvaluateJSReply::StringValue(String::from(jsstring_to_str(*cx, rval.to_string())))
         } else if rval.is_null() {
             EvaluateJSReply::NullValue
         } else {
             assert!(rval.is_object());
 
-            rooted!(in(cx) let obj = rval.to_object());
-            let class_name = CStr::from_ptr(ObjectClassName(cx, obj.handle()));
+            rooted!(in(*cx) let obj = rval.to_object());
+            let class_name = CStr::from_ptr(ObjectClassName(*cx, obj.handle()));
             let class_name = str::from_utf8(class_name.to_bytes()).unwrap();
 
             EvaluateJSReply::ActorValue {
diff --git a/components/script/dom/audiobuffer.rs b/components/script/dom/audiobuffer.rs
index a5b8dfbc8c8..4b113a200fe 100644
--- a/components/script/dom/audiobuffer.rs
+++ b/components/script/dom/audiobuffer.rs
@@ -173,15 +173,15 @@ impl AudioBuffer {
 
             // Step 2.
             let channel_data = unsafe {
-                typedarray!(in(cx) let array: Float32Array = channel.get());
+                typedarray!(in(*cx) let array: Float32Array = channel.get());
                 if let Ok(array) = array {
                     let data = array.to_vec();
                     let mut is_shared = false;
-                    rooted!(in (cx) let view_buffer =
-                        JS_GetArrayBufferViewBuffer(cx, channel.handle(), &mut is_shared));
+                    rooted!(in (*cx) let view_buffer =
+                        JS_GetArrayBufferViewBuffer(*cx, channel.handle(), &mut is_shared));
                     // This buffer is always created unshared
                     debug_assert!(!is_shared);
-                    let _ = DetachArrayBuffer(cx, view_buffer.handle());
+                    let _ = DetachArrayBuffer(*cx, view_buffer.handle());
                     data
                 } else {
                     return None;
@@ -272,7 +272,7 @@ impl AudioBufferMethods for AudioBuffer {
         // We either copy form js_channels or shared_channels.
         let js_channel = self.js_channels.borrow()[channel_number].get();
         if !js_channel.is_null() {
-            typedarray!(in(cx) let array: Float32Array = js_channel);
+            typedarray!(in(*cx) let array: Float32Array = js_channel);
             if let Ok(array) = array {
                 let data = unsafe { array.as_slice() };
                 dest.extend_from_slice(&data[offset..offset + bytes_to_copy]);
@@ -307,7 +307,7 @@ impl AudioBufferMethods for AudioBuffer {
         }
 
         let cx = self.global().get_cx();
-        if unsafe { !self.restore_js_channel_data(cx) } {
+        if unsafe { !self.restore_js_channel_data(*cx) } {
             return Err(Error::JSFailed);
         }
 
@@ -317,7 +317,7 @@ impl AudioBufferMethods for AudioBuffer {
             return Err(Error::IndexSize);
         }
 
-        typedarray!(in(cx) let js_channel: Float32Array = js_channel);
+        typedarray!(in(*cx) let js_channel: Float32Array = js_channel);
         if let Ok(mut js_channel) = js_channel {
             let bytes_to_copy = min(self.length - start_in_channel, source.len() as u32) as usize;
             let js_channel_data = unsafe { js_channel.as_mut_slice() };
diff --git a/components/script/dom/bindings/callback.rs b/components/script/dom/bindings/callback.rs
index 77f6880e35a..03b8f326f55 100644
--- a/components/script/dom/bindings/callback.rs
+++ b/components/script/dom/bindings/callback.rs
@@ -255,8 +255,8 @@ impl CallSetup {
         let ais = callback.incumbent().map(AutoIncumbentScript::new);
         CallSetup {
             exception_global: global,
-            cx: cx,
-            old_realm: unsafe { EnterRealm(cx, callback.callback()) },
+            cx: *cx,
+            old_realm: unsafe { EnterRealm(*cx, callback.callback()) },
             handling: handling,
             entry_script: Some(aes),
             incumbent_script: ais,
diff --git a/components/script/dom/bindings/htmlconstructor.rs b/components/script/dom/bindings/htmlconstructor.rs
index f976a09ee91..6faa4f6211c 100644
--- a/components/script/dom/bindings/htmlconstructor.rs
+++ b/components/script/dom/bindings/htmlconstructor.rs
@@ -100,7 +100,7 @@ where
     // Step 2 is checked in the generated caller code
 
     // Step 3
-    rooted!(in(window.get_cx()) let new_target = call_args.new_target().to_object());
+    rooted!(in(*window.get_cx()) let new_target = call_args.new_target().to_object());
     let definition = match registry.lookup_definition_by_constructor(new_target.handle()) {
         Some(definition) => definition,
         None => {
@@ -110,15 +110,15 @@ where
         },
     };
 
-    rooted!(in(window.get_cx()) let callee = UnwrapObjectStatic(call_args.callee()));
+    rooted!(in(*window.get_cx()) let callee = UnwrapObjectStatic(call_args.callee()));
     if callee.is_null() {
         return Err(Error::Security);
     }
 
     {
-        let _ac = JSAutoRealm::new(window.get_cx(), callee.get());
-        rooted!(in(window.get_cx()) let mut constructor = ptr::null_mut::<JSObject>());
-        rooted!(in(window.get_cx()) let global_object = CurrentGlobalOrNull(window.get_cx()));
+        let _ac = JSAutoRealm::new(*window.get_cx(), callee.get());
+        rooted!(in(*window.get_cx()) let mut constructor = ptr::null_mut::<JSObject>());
+        rooted!(in(*window.get_cx()) let global_object = CurrentGlobalOrNull(*window.get_cx()));
 
         if definition.is_autonomous() {
             // Step 4
@@ -126,7 +126,7 @@ where
 
             // Retrieve the constructor object for HTMLElement
             HTMLElementBinding::GetConstructorObject(
-                SafeJSContext::from_ptr(window.get_cx()),
+                window.get_cx(),
                 global_object.handle(),
                 constructor.handle_mut(),
             );
@@ -134,7 +134,7 @@ where
             // Step 5
             get_constructor_object_from_local_name(
                 definition.local_name.clone(),
-                window.get_cx(),
+                *window.get_cx(),
                 global_object.handle(),
                 constructor.handle_mut(),
             );
diff --git a/components/script/dom/bindings/reflector.rs b/components/script/dom/bindings/reflector.rs
index a66ff114226..dc13fca77b0 100644
--- a/components/script/dom/bindings/reflector.rs
+++ b/components/script/dom/bindings/reflector.rs
@@ -7,7 +7,7 @@
 use crate::dom::bindings::conversions::DerivedFrom;
 use crate::dom::bindings::root::DomRoot;
 use crate::dom::globalscope::GlobalScope;
-use crate::script_runtime::JSContext as SafeJSContext;
+use crate::script_runtime::JSContext;
 use js::jsapi::{Heap, JSObject};
 use js::rust::HandleObject;
 use std::default::Default;
@@ -17,20 +17,14 @@ use std::default::Default;
 pub fn reflect_dom_object<T, U>(
     obj: Box<T>,
     global: &U,
-    wrap_fn: unsafe fn(SafeJSContext, &GlobalScope, Box<T>) -> DomRoot<T>,
+    wrap_fn: unsafe fn(JSContext, &GlobalScope, Box<T>) -> DomRoot<T>,
 ) -> DomRoot<T>
 where
     T: DomObject,
     U: DerivedFrom<GlobalScope>,
 {
     let global_scope = global.upcast();
-    unsafe {
-        wrap_fn(
-            SafeJSContext::from_ptr(global_scope.get_cx()),
-            global_scope,
-            obj,
-        )
-    }
+    unsafe { wrap_fn(global_scope.get_cx(), global_scope, obj) }
 }
 
 /// A struct to store a reference to the reflector of a DOM object.
diff --git a/components/script/dom/bindings/structuredclone.rs b/components/script/dom/bindings/structuredclone.rs
index 167b375dbc7..f35a4af7210 100644
--- a/components/script/dom/bindings/structuredclone.rs
+++ b/components/script/dom/bindings/structuredclone.rs
@@ -321,7 +321,7 @@ impl StructuredCloneData {
             WriteBytesToJSStructuredCloneData(data as *const u8, nbytes, scdata);
 
             assert!(JS_ReadStructuredClone(
-                cx,
+                *cx,
                 scdata,
                 JS_STRUCTURED_CLONE_VERSION,
                 StructuredCloneScope::DifferentProcess,
diff --git a/components/script/dom/create.rs b/components/script/dom/create.rs
index 5ca05d2f713..18c9504a245 100644
--- a/components/script/dom/create.rs
+++ b/components/script/dom/create.rs
@@ -157,9 +157,9 @@ fn create_html_element(
                             // Step 6.1.1
                             unsafe {
                                 let _ac =
-                                    JSAutoRealm::new(cx, global.reflector().get_jsobject().get());
-                                throw_dom_exception(cx, &global, error);
-                                report_pending_exception(cx, true);
+                                    JSAutoRealm::new(*cx, global.reflector().get_jsobject().get());
+                                throw_dom_exception(*cx, &global, error);
+                                report_pending_exception(*cx, true);
                             }
 
                             // Step 6.1.2
diff --git a/components/script/dom/customelementregistry.rs b/components/script/dom/customelementregistry.rs
index 6b2f8992c0a..2603768ed83 100644
--- a/components/script/dom/customelementregistry.rs
+++ b/components/script/dom/customelementregistry.rs
@@ -145,7 +145,7 @@ impl CustomElementRegistry {
         unsafe {
             // Step 10.1
             if !JS_GetProperty(
-                global_scope.get_cx(),
+                *global_scope.get_cx(),
                 constructor,
                 b"prototype\0".as_ptr() as *const _,
                 prototype,
@@ -171,10 +171,14 @@ impl CustomElementRegistry {
 
         // Step 4
         Ok(LifecycleCallbacks {
-            connected_callback: get_callback(cx, prototype, b"connectedCallback\0")?,
-            disconnected_callback: get_callback(cx, prototype, b"disconnectedCallback\0")?,
-            adopted_callback: get_callback(cx, prototype, b"adoptedCallback\0")?,
-            attribute_changed_callback: get_callback(cx, prototype, b"attributeChangedCallback\0")?,
+            connected_callback: get_callback(*cx, prototype, b"connectedCallback\0")?,
+            disconnected_callback: get_callback(*cx, prototype, b"disconnectedCallback\0")?,
+            adopted_callback: get_callback(*cx, prototype, b"adoptedCallback\0")?,
+            attribute_changed_callback: get_callback(
+                *cx,
+                prototype,
+                b"attributeChangedCallback\0",
+            )?,
         })
     }
 
@@ -183,10 +187,10 @@ impl CustomElementRegistry {
     #[allow(unsafe_code)]
     fn get_observed_attributes(&self, constructor: HandleObject) -> Fallible<Vec<DOMString>> {
         let cx = self.window.get_cx();
-        rooted!(in(cx) let mut observed_attributes = UndefinedValue());
+        rooted!(in(*cx) let mut observed_attributes = UndefinedValue());
         if unsafe {
             !JS_GetProperty(
-                cx,
+                *cx,
                 constructor,
                 b"observedAttributes\0".as_ptr() as *const _,
                 observed_attributes.handle_mut(),
@@ -201,7 +205,7 @@ impl CustomElementRegistry {
 
         let conversion = unsafe {
             FromJSValConvertible::from_jsval(
-                cx,
+                *cx,
                 observed_attributes.handle(),
                 StringificationBehavior::Default,
             )
@@ -258,12 +262,12 @@ impl CustomElementRegistryMethods for CustomElementRegistry {
         options: &ElementDefinitionOptions,
     ) -> ErrorResult {
         let cx = self.window.get_cx();
-        rooted!(in(cx) let constructor = constructor_.callback());
+        rooted!(in(*cx) let constructor = constructor_.callback());
         let name = LocalName::from(&*name);
 
         // Step 1
         // We must unwrap the constructor as all wrappers are constructable if they are callable.
-        rooted!(in(cx) let unwrapped_constructor = unsafe { UnwrapObjectStatic(constructor.get()) });
+        rooted!(in(*cx) let unwrapped_constructor = unsafe { UnwrapObjectStatic(constructor.get()) });
 
         if unwrapped_constructor.is_null() {
             // We do not have permission to access the unwrapped constructor.
@@ -326,9 +330,9 @@ impl CustomElementRegistryMethods for CustomElementRegistry {
         self.element_definition_is_running.set(true);
 
         // Steps 10.1 - 10.2
-        rooted!(in(cx) let mut prototype = UndefinedValue());
+        rooted!(in(*cx) let mut prototype = UndefinedValue());
         {
-            let _ac = JSAutoRealm::new(cx, constructor.get());
+            let _ac = JSAutoRealm::new(*cx, constructor.get());
             if let Err(error) = self.check_prototype(constructor.handle(), prototype.handle_mut()) {
                 self.element_definition_is_running.set(false);
                 return Err(error);
@@ -336,9 +340,9 @@ impl CustomElementRegistryMethods for CustomElementRegistry {
         };
 
         // Steps 10.3 - 10.4
-        rooted!(in(cx) let proto_object = prototype.to_object());
+        rooted!(in(*cx) let proto_object = prototype.to_object());
         let callbacks = {
-            let _ac = JSAutoRealm::new(cx, proto_object.get());
+            let _ac = JSAutoRealm::new(*cx, proto_object.get());
             match unsafe { self.get_callbacks(proto_object.handle()) } {
                 Ok(callbacks) => callbacks,
                 Err(error) => {
@@ -350,7 +354,7 @@ impl CustomElementRegistryMethods for CustomElementRegistry {
 
         // Step 10.5 - 10.6
         let observed_attributes = if callbacks.attribute_changed_callback.is_some() {
-            let _ac = JSAutoRealm::new(cx, constructor.get());
+            let _ac = JSAutoRealm::new(*cx, constructor.get());
             match self.get_observed_attributes(constructor.handle()) {
                 Ok(attributes) => attributes,
                 Err(error) => {
@@ -523,20 +527,20 @@ impl CustomElementDefinition {
         let window = document.window();
         let cx = window.get_cx();
         // Step 2
-        rooted!(in(cx) let constructor = ObjectValue(self.constructor.callback()));
-        rooted!(in(cx) let mut element = ptr::null_mut::<JSObject>());
+        rooted!(in(*cx) let constructor = ObjectValue(self.constructor.callback()));
+        rooted!(in(*cx) let mut element = ptr::null_mut::<JSObject>());
         {
             // Go into the constructor's compartment
-            let _ac = JSAutoRealm::new(cx, self.constructor.callback());
+            let _ac = JSAutoRealm::new(*cx, self.constructor.callback());
             let args = HandleValueArray::new();
-            if unsafe { !Construct1(cx, constructor.handle(), &args, element.handle_mut()) } {
+            if unsafe { !Construct1(*cx, constructor.handle(), &args, element.handle_mut()) } {
                 return Err(Error::JSFailed);
             }
         }
 
-        rooted!(in(cx) let element_val = ObjectValue(element.get()));
+        rooted!(in(*cx) let element_val = ObjectValue(element.get()));
         let element: DomRoot<Element> =
-            match unsafe { DomRoot::from_jsval(cx, element_val.handle(), ()) } {
+            match unsafe { DomRoot::from_jsval(*cx, element_val.handle(), ()) } {
                 Ok(ConversionResult::Success(element)) => element,
                 Ok(ConversionResult::Failure(..)) => {
                     return Err(Error::Type(
@@ -627,8 +631,8 @@ pub fn upgrade_element(definition: Rc<CustomElementDefinition>, element: &Elemen
         let global = GlobalScope::current().expect("No current global");
         let cx = global.get_cx();
         unsafe {
-            throw_dom_exception(cx, &global, error);
-            report_pending_exception(cx, true);
+            throw_dom_exception(*cx, &global, error);
+            report_pending_exception(*cx, true);
         }
         return;
     }
@@ -649,20 +653,20 @@ fn run_upgrade_constructor(
 ) -> ErrorResult {
     let window = window_from_node(element);
     let cx = window.get_cx();
-    rooted!(in(cx) let constructor_val = ObjectValue(constructor.callback()));
-    rooted!(in(cx) let mut element_val = UndefinedValue());
+    rooted!(in(*cx) let constructor_val = ObjectValue(constructor.callback()));
+    rooted!(in(*cx) let mut element_val = UndefinedValue());
     unsafe {
-        element.to_jsval(cx, element_val.handle_mut());
+        element.to_jsval(*cx, element_val.handle_mut());
     }
-    rooted!(in(cx) let mut construct_result = ptr::null_mut::<JSObject>());
+    rooted!(in(*cx) let mut construct_result = ptr::null_mut::<JSObject>());
     {
         // Go into the constructor's compartment
-        let _ac = JSAutoRealm::new(cx, constructor.callback());
+        let _ac = JSAutoRealm::new(*cx, constructor.callback());
         let args = HandleValueArray::new();
         // Step 7.1
         if unsafe {
             !Construct1(
-                cx,
+                *cx,
                 constructor_val.handle(),
                 &args,
                 construct_result.handle_mut(),
@@ -672,10 +676,10 @@ fn run_upgrade_constructor(
         }
         // Step 7.2
         let mut same = false;
-        rooted!(in(cx) let construct_result_val = ObjectValue(construct_result.get()));
+        rooted!(in(*cx) let construct_result_val = ObjectValue(construct_result.get()));
         if unsafe {
             !SameValue(
-                cx,
+                *cx,
                 construct_result_val.handle(),
                 element_val.handle(),
                 &mut same,
@@ -863,30 +867,30 @@ impl CustomElementReactionStack {
                 let cx = element.global().get_cx();
 
                 let local_name = DOMString::from(&*local_name);
-                rooted!(in(cx) let mut name_value = UndefinedValue());
+                rooted!(in(*cx) let mut name_value = UndefinedValue());
                 unsafe {
-                    local_name.to_jsval(cx, name_value.handle_mut());
+                    local_name.to_jsval(*cx, name_value.handle_mut());
                 }
 
-                rooted!(in(cx) let mut old_value = NullValue());
+                rooted!(in(*cx) let mut old_value = NullValue());
                 if let Some(old_val) = old_val {
                     unsafe {
-                        old_val.to_jsval(cx, old_value.handle_mut());
+                        old_val.to_jsval(*cx, old_value.handle_mut());
                     }
                 }
 
-                rooted!(in(cx) let mut value = NullValue());
+                rooted!(in(*cx) let mut value = NullValue());
                 if let Some(val) = val {
                     unsafe {
-                        val.to_jsval(cx, value.handle_mut());
+                        val.to_jsval(*cx, value.handle_mut());
                     }
                 }
 
-                rooted!(in(cx) let mut namespace_value = NullValue());
+                rooted!(in(*cx) let mut namespace_value = NullValue());
                 if namespace != ns!() {
                     let namespace = DOMString::from(&*namespace);
                     unsafe {
-                        namespace.to_jsval(cx, namespace_value.handle_mut());
+                        namespace.to_jsval(*cx, namespace_value.handle_mut());
                     }
                 }
 
diff --git a/components/script/dom/dedicatedworkerglobalscope.rs b/components/script/dom/dedicatedworkerglobalscope.rs
index 2c6042333a6..a3adde75498 100644
--- a/components/script/dom/dedicatedworkerglobalscope.rs
+++ b/components/script/dom/dedicatedworkerglobalscope.rs
@@ -405,7 +405,7 @@ impl DedicatedWorkerGlobalScope {
 
                 unsafe {
                     // Handle interrupt requests
-                    JS_AddInterruptCallback(scope.get_cx(), Some(interrupt_callback));
+                    JS_AddInterruptCallback(*scope.get_cx(), Some(interrupt_callback));
                 }
 
                 if scope.is_closing() {
@@ -466,7 +466,7 @@ impl DedicatedWorkerGlobalScope {
                 let scope = self.upcast::<WorkerGlobalScope>();
                 let target = self.upcast();
                 let _ac = enter_realm(self);
-                rooted!(in(scope.get_cx()) let mut message = UndefinedValue());
+                rooted!(in(*scope.get_cx()) let mut message = UndefinedValue());
                 data.read(scope.upcast(), message.handle_mut());
                 MessageEvent::dispatch_jsval(target, scope.upcast(), message.handle(), None, None);
             },
diff --git a/components/script/dom/dissimilaroriginwindow.rs b/components/script/dom/dissimilaroriginwindow.rs
index 8724516acec..8f7eda58100 100644
--- a/components/script/dom/dissimilaroriginwindow.rs
+++ b/components/script/dom/dissimilaroriginwindow.rs
@@ -68,7 +68,7 @@ impl DissimilarOriginWindow {
             window_proxy: Dom::from_ref(window_proxy),
             location: Default::default(),
         });
-        unsafe { DissimilarOriginWindowBinding::Wrap(JSContext::from_ptr(cx), win) }
+        unsafe { DissimilarOriginWindowBinding::Wrap(cx, win) }
     }
 
     pub fn window_proxy(&self) -> DomRoot<WindowProxy> {
diff --git a/components/script/dom/documentorshadowroot.rs b/components/script/dom/documentorshadowroot.rs
index 9b57dd32bf6..594801584c8 100644
--- a/components/script/dom/documentorshadowroot.rs
+++ b/components/script/dom/documentorshadowroot.rs
@@ -131,7 +131,7 @@ impl DocumentOrShadowRoot {
             .first()
         {
             Some(address) => {
-                let js_runtime = unsafe { JS_GetRuntime(self.window.get_cx()) };
+                let js_runtime = unsafe { JS_GetRuntime(*self.window.get_cx()) };
                 let node = unsafe { node::from_untrusted_node_address(js_runtime, *address) };
                 let parent_node = node.GetParentNode().unwrap();
                 let element_ref = node
@@ -167,7 +167,7 @@ impl DocumentOrShadowRoot {
             return vec![];
         }
 
-        let js_runtime = unsafe { JS_GetRuntime(self.window.get_cx()) };
+        let js_runtime = unsafe { JS_GetRuntime(*self.window.get_cx()) };
 
         // Step 1 and Step 3
         let nodes = self.nodes_from_point(point, NodesFromPointQueryType::All);
diff --git a/components/script/dom/eventsource.rs b/components/script/dom/eventsource.rs
index 64c88496a46..02283a3c190 100644
--- a/components/script/dom/eventsource.rs
+++ b/components/script/dom/eventsource.rs
@@ -223,10 +223,10 @@ 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(*event_source.global().get_cx()) let mut data = UndefinedValue());
             unsafe {
                 self.data
-                    .to_jsval(event_source.global().get_cx(), data.handle_mut())
+                    .to_jsval(*event_source.global().get_cx(), data.handle_mut())
             };
             MessageEvent::new(
                 &*event_source.global(),
diff --git a/components/script/dom/eventtarget.rs b/components/script/dom/eventtarget.rs
index 144f918b8d6..12cf7d0253b 100644
--- a/components/script/dom/eventtarget.rs
+++ b/components/script/dom/eventtarget.rs
@@ -33,7 +33,6 @@ use crate::dom::globalscope::GlobalScope;
 use crate::dom::node::document_from_node;
 use crate::dom::virtualmethods::VirtualMethods;
 use crate::dom::window::Window;
-use crate::script_runtime::JSContext;
 use dom_struct::dom_struct;
 use fnv::FnvHasher;
 use js::jsapi::{JSAutoRealm, JSFunction, JS_GetFunctionObject, SourceText};
@@ -151,7 +150,6 @@ pub enum CompiledEventListener {
 }
 
 impl CompiledEventListener {
-    #[allow(unsafe_code)]
     // https://html.spec.whatwg.org/multipage/#the-event-handler-processing-algorithm
     pub fn call_or_handle_event<T: DomObject>(
         &self,
@@ -169,7 +167,7 @@ impl CompiledEventListener {
                     CommonEventHandler::ErrorEventHandler(ref handler) => {
                         if let Some(event) = event.downcast::<ErrorEvent>() {
                             let cx = object.global().get_cx();
-                            rooted!(in(cx) let error = unsafe { event.Error(JSContext::from_ptr(cx)) });
+                            rooted!(in(*cx) let error = event.Error(cx));
                             let return_value = handler.Call_(
                                 object,
                                 EventOrString::String(event.Message()),
@@ -181,7 +179,7 @@ impl CompiledEventListener {
                             );
                             // Step 4
                             if let Ok(return_value) = return_value {
-                                rooted!(in(cx) let return_value = return_value);
+                                rooted!(in(*cx) let return_value = return_value);
                                 if return_value.handle().is_boolean() &&
                                     return_value.handle().to_boolean() == true
                                 {
@@ -226,7 +224,7 @@ impl CompiledEventListener {
                     CommonEventHandler::EventHandler(ref handler) => {
                         if let Ok(value) = handler.Call_(object, event, exception_handle) {
                             let cx = object.global().get_cx();
-                            rooted!(in(cx) let value = value);
+                            rooted!(in(*cx) let value = value);
                             let value = value.handle();
 
                             //Step 4
@@ -503,16 +501,16 @@ impl EventTarget {
         };
 
         let cx = window.get_cx();
-        let options = CompileOptionsWrapper::new(cx, url_serialized.as_ptr(), handler.line as u32);
+        let options = CompileOptionsWrapper::new(*cx, url_serialized.as_ptr(), handler.line as u32);
         // TODO step 1.10.1-3 (document, form owner, element in scope chain)
 
-        let scopechain = AutoObjectVectorWrapper::new(cx);
+        let scopechain = AutoObjectVectorWrapper::new(*cx);
 
         let _ac = enter_realm(&*window);
-        rooted!(in(cx) let mut handler = ptr::null_mut::<JSFunction>());
+        rooted!(in(*cx) let mut handler = ptr::null_mut::<JSFunction>());
         let rv = unsafe {
             CompileFunction(
-                cx,
+                *cx,
                 scopechain.ptr,
                 options.ptr,
                 name.as_ptr(),
@@ -530,9 +528,9 @@ impl EventTarget {
         if !rv || handler.get().is_null() {
             // Step 1.8.2
             unsafe {
-                let _ac = JSAutoRealm::new(cx, self.reflector().get_jsobject().get());
+                let _ac = JSAutoRealm::new(*cx, self.reflector().get_jsobject().get());
                 // FIXME(#13152): dispatch error event.
-                report_pending_exception(cx, false);
+                report_pending_exception(*cx, false);
             }
             // Step 1.8.1 / 1.8.3
             return None;
@@ -544,16 +542,16 @@ impl EventTarget {
         // Step 1.14
         if is_error {
             Some(CommonEventHandler::ErrorEventHandler(unsafe {
-                OnErrorEventHandlerNonNull::new(JSContext::from_ptr(cx), funobj)
+                OnErrorEventHandlerNonNull::new(cx, funobj)
             }))
         } else {
             if ty == &atom!("beforeunload") {
                 Some(CommonEventHandler::BeforeUnloadEventHandler(unsafe {
-                    OnBeforeUnloadEventHandlerNonNull::new(JSContext::from_ptr(cx), funobj)
+                    OnBeforeUnloadEventHandlerNonNull::new(cx, funobj)
                 }))
             } else {
                 Some(CommonEventHandler::EventHandler(unsafe {
-                    EventHandlerNonNull::new(JSContext::from_ptr(cx), funobj)
+                    EventHandlerNonNull::new(cx, funobj)
                 }))
             }
         }
@@ -568,7 +566,7 @@ impl EventTarget {
 
         let event_listener = listener.map(|listener| {
             InlineEventListener::Compiled(CommonEventHandler::EventHandler(unsafe {
-                EventHandlerNonNull::new(JSContext::from_ptr(cx), listener.callback())
+                EventHandlerNonNull::new(cx, listener.callback())
             }))
         });
         self.set_inline_event_listener(Atom::from(ty), event_listener);
@@ -583,7 +581,7 @@ impl EventTarget {
 
         let event_listener = listener.map(|listener| {
             InlineEventListener::Compiled(CommonEventHandler::ErrorEventHandler(unsafe {
-                OnErrorEventHandlerNonNull::new(JSContext::from_ptr(cx), listener.callback())
+                OnErrorEventHandlerNonNull::new(cx, listener.callback())
             }))
         });
         self.set_inline_event_listener(Atom::from(ty), event_listener);
@@ -601,7 +599,7 @@ impl EventTarget {
 
         let event_listener = listener.map(|listener| {
             InlineEventListener::Compiled(CommonEventHandler::BeforeUnloadEventHandler(unsafe {
-                OnBeforeUnloadEventHandlerNonNull::new(JSContext::from_ptr(cx), listener.callback())
+                OnBeforeUnloadEventHandlerNonNull::new(cx, listener.callback())
             }))
         });
         self.set_inline_event_listener(Atom::from(ty), event_listener);
@@ -613,10 +611,7 @@ impl EventTarget {
         let listener = self.get_inline_event_listener(&Atom::from(ty));
         unsafe {
             listener.map(|listener| {
-                CallbackContainer::new(
-                    JSContext::from_ptr(cx),
-                    listener.parent().callback_holder().get(),
-                )
+                CallbackContainer::new(cx, listener.parent().callback_holder().get())
             })
         }
     }
diff --git a/components/script/dom/filereader.rs b/components/script/dom/filereader.rs
index 0e158dedbab..fdba0e0aa75 100644
--- a/components/script/dom/filereader.rs
+++ b/components/script/dom/filereader.rs
@@ -266,7 +266,7 @@ impl FileReader {
                 let _ac = enter_realm(&*fr);
                 FileReader::perform_readasarraybuffer(
                     &fr.result,
-                    fr.global().get_cx(),
+                    *fr.global().get_cx(),
                     data,
                     &blob_contents,
                 )
diff --git a/components/script/dom/gamepad.rs b/components/script/dom/gamepad.rs
index 08160bfd3ad..60a73a691fd 100644
--- a/components/script/dom/gamepad.rs
+++ b/components/script/dom/gamepad.rs
@@ -99,9 +99,9 @@ impl Gamepad {
         );
 
         let cx = global.get_cx();
-        rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
+        rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
         unsafe {
-            let _ = Float64Array::create(cx, CreateWith::Slice(&state.axes), array.handle_mut());
+            let _ = Float64Array::create(*cx, CreateWith::Slice(&state.axes), array.handle_mut());
         }
         gamepad.axes.set(array.get());
 
@@ -173,7 +173,7 @@ impl Gamepad {
         self.timestamp.set(state.timestamp);
         unsafe {
             let cx = self.global().get_cx();
-            typedarray!(in(cx) let axes: Float64Array = self.axes.get());
+            typedarray!(in(*cx) let axes: Float64Array = self.axes.get());
             if let Ok(mut array) = axes {
                 array.update(&state.axes);
             }
diff --git a/components/script/dom/globalscope.rs b/components/script/dom/globalscope.rs
index 385939000bc..ddf7dfc61cc 100644
--- a/components/script/dom/globalscope.rs
+++ b/components/script/dom/globalscope.rs
@@ -26,7 +26,7 @@ use crate::dom::window::Window;
 use crate::dom::workerglobalscope::WorkerGlobalScope;
 use crate::dom::workletglobalscope::WorkletGlobalScope;
 use crate::microtask::{Microtask, MicrotaskQueue};
-use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptPort};
+use crate::script_runtime::{CommonScriptMsg, JSContext as SafeJSContext, ScriptChan, ScriptPort};
 use crate::script_thread::{MainThreadScriptChan, ScriptThread};
 use crate::task::TaskCanceller;
 use crate::task_source::dom_manipulation::DOMManipulationTaskSource;
@@ -311,8 +311,8 @@ impl GlobalScope {
     }
 
     #[allow(unsafe_code)]
-    pub fn get_cx(&self) -> *mut JSContext {
-        Runtime::get()
+    pub fn get_cx(&self) -> SafeJSContext {
+        unsafe { SafeJSContext::from_ptr(Runtime::get()) }
     }
 
     pub fn crypto(&self) -> DomRoot<Crypto> {
@@ -571,14 +571,14 @@ impl GlobalScope {
                 let globalhandle = self.reflector().get_jsobject();
                 let filename = CString::new(filename).unwrap();
 
-                let _ac = JSAutoRealm::new(cx, globalhandle.get());
+                let _ac = JSAutoRealm::new(*cx, globalhandle.get());
                 let _aes = AutoEntryScript::new(self);
-                let options = CompileOptionsWrapper::new(cx, filename.as_ptr(), line_number);
+                let options = CompileOptionsWrapper::new(*cx, filename.as_ptr(), line_number);
 
                 debug!("evaluating Dom string");
                 let result = unsafe {
                     EvaluateUtf8(
-                        cx,
+                        *cx,
                         options.ptr,
                         code.as_ptr() as *const _,
                         code.len() as libc::size_t,
@@ -588,7 +588,7 @@ impl GlobalScope {
 
                 if !result {
                     debug!("error evaluating Dom string");
-                    unsafe { report_pending_exception(cx, true) };
+                    unsafe { report_pending_exception(*cx, true) };
                 }
 
                 maybe_resume_unwind();
@@ -681,7 +681,7 @@ impl GlobalScope {
     pub fn perform_a_microtask_checkpoint(&self) {
         unsafe {
             self.microtask_queue.checkpoint(
-                self.get_cx(),
+                *self.get_cx(),
                 |_| Some(DomRoot::from_ref(self)),
                 vec![DomRoot::from_ref(self)],
             );
@@ -692,7 +692,7 @@ impl GlobalScope {
     #[allow(unsafe_code)]
     pub fn enqueue_microtask(&self, job: Microtask) {
         unsafe {
-            self.microtask_queue.enqueue(job, self.get_cx());
+            self.microtask_queue.enqueue(job, *self.get_cx());
         }
     }
 
diff --git a/components/script/dom/history.rs b/components/script/dom/history.rs
index 4bbcba64bad..583c58a00f1 100644
--- a/components/script/dom/history.rs
+++ b/components/script/dom/history.rs
@@ -117,7 +117,7 @@ impl History {
         match serialized_data {
             Some(serialized_data) => {
                 let global_scope = self.window.upcast::<GlobalScope>();
-                rooted!(in(global_scope.get_cx()) let mut state = UndefinedValue());
+                rooted!(in(*global_scope.get_cx()) let mut state = UndefinedValue());
                 StructuredCloneData::Vector(serialized_data)
                     .read(&global_scope, state.handle_mut());
                 self.state.set(state.get());
diff --git a/components/script/dom/htmlscriptelement.rs b/components/script/dom/htmlscriptelement.rs
index 4325add0212..1af49a42f79 100644
--- a/components/script/dom/htmlscriptelement.rs
+++ b/components/script/dom/htmlscriptelement.rs
@@ -654,7 +654,7 @@ impl HTMLScriptElement {
         } else {
             self.line_number as u32
         };
-        rooted!(in(window.get_cx()) let mut rval = UndefinedValue());
+        rooted!(in(*window.get_cx()) let mut rval = UndefinedValue());
         let global = window.upcast::<GlobalScope>();
         global.evaluate_script_on_global_with_result(
             &script.text,
diff --git a/components/script/dom/imagedata.rs b/components/script/dom/imagedata.rs
index 8546f73e5cf..52851fdce36 100644
--- a/components/script/dom/imagedata.rs
+++ b/components/script/dom/imagedata.rs
@@ -41,7 +41,7 @@ impl ImageData {
         let len = width * height * 4;
         unsafe {
             let cx = global.get_cx();
-            rooted!(in (cx) let mut js_object = ptr::null_mut::<JSObject>());
+            rooted!(in (*cx) let mut js_object = ptr::null_mut::<JSObject>());
             let data = match data {
                 Some(ref mut d) => {
                     d.resize(len as usize, 0);
@@ -49,7 +49,7 @@ impl ImageData {
                 },
                 None => CreateWith::Length(len),
             };
-            Uint8ClampedArray::create(cx, data, js_object.handle_mut()).unwrap();
+            Uint8ClampedArray::create(*cx, data, js_object.handle_mut()).unwrap();
             Self::new_with_jsobject(global, width, Some(height), Some(js_object.get()))
         }
     }
@@ -70,7 +70,7 @@ impl ImageData {
         // checking jsobject type and verifying (height * width * 4 == jsobject.byte_len())
         if let Some(jsobject) = opt_jsobject {
             let cx = global.get_cx();
-            typedarray!(in(cx) let array_res: Uint8ClampedArray = jsobject);
+            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())
             })?;
@@ -110,8 +110,8 @@ impl ImageData {
         } else {
             let len = width * height * 4;
             let cx = global.get_cx();
-            rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
-            Uint8ClampedArray::create(cx, CreateWith::Length(len), array.handle_mut()).unwrap();
+            rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
+            Uint8ClampedArray::create(*cx, CreateWith::Length(len), array.handle_mut()).unwrap();
             (*imagedata).data.set(array.get());
         }
 
diff --git a/components/script/dom/paintworkletglobalscope.rs b/components/script/dom/paintworkletglobalscope.rs
index 296ad4998eb..bc04ab63440 100644
--- a/components/script/dom/paintworkletglobalscope.rs
+++ b/components/script/dom/paintworkletglobalscope.rs
@@ -253,12 +253,12 @@ impl PaintWorkletGlobalScope {
         );
 
         let cx = self.worklet_global.get_cx();
-        let _ac = JSAutoRealm::new(cx, self.worklet_global.reflector().get_jsobject().get());
+        let _ac = JSAutoRealm::new(*cx, self.worklet_global.reflector().get_jsobject().get());
 
         // TODO: Steps 1-2.1.
         // Step 2.2-5.1.
-        rooted!(in(cx) let mut class_constructor = UndefinedValue());
-        rooted!(in(cx) let mut paint_function = UndefinedValue());
+        rooted!(in(*cx) let mut class_constructor = UndefinedValue());
+        rooted!(in(*cx) let mut paint_function = UndefinedValue());
         let rendering_context = match self.paint_definitions.borrow().get(name) {
             None => {
                 // Step 2.2.
@@ -282,21 +282,21 @@ impl PaintWorkletGlobalScope {
         // prepopulate the paint instance in `RegisterPaint`, to avoid calling it in
         // the primary worklet thread.
         // https://github.com/servo/servo/issues/17377
-        rooted!(in(cx) let mut paint_instance = UndefinedValue());
+        rooted!(in(*cx) let mut paint_instance = UndefinedValue());
         match self.paint_class_instances.borrow_mut().entry(name.clone()) {
             Entry::Occupied(entry) => paint_instance.set(entry.get().get()),
             Entry::Vacant(entry) => {
                 // Step 5.2-5.3
                 let args = HandleValueArray::new();
-                rooted!(in(cx) let mut result = null_mut::<JSObject>());
+                rooted!(in(*cx) let mut result = null_mut::<JSObject>());
                 unsafe {
-                    Construct1(cx, class_constructor.handle(), &args, result.handle_mut());
+                    Construct1(*cx, class_constructor.handle(), &args, result.handle_mut());
                 }
                 paint_instance.set(ObjectValue(result.get()));
-                if unsafe { JS_IsExceptionPending(cx) } {
+                if unsafe { JS_IsExceptionPending(*cx) } {
                     debug!("Paint constructor threw an exception {}.", name);
                     unsafe {
-                        JS_ClearPendingException(cx);
+                        JS_ClearPendingException(*cx);
                     }
                     self.paint_definitions
                         .borrow_mut()
@@ -333,7 +333,7 @@ impl PaintWorkletGlobalScope {
             .collect();
         let arguments_value_array =
             unsafe { HandleValueArray::from_rooted_slice(&*arguments_value_vec) };
-        rooted!(in(cx) let argument_object = unsafe { JS_NewArrayObject(cx, &arguments_value_array) });
+        rooted!(in(*cx) let argument_object = unsafe { JS_NewArrayObject(*cx, &arguments_value_array) });
 
         let args_slice = [
             ObjectValue(rendering_context.reflector().get_jsobject().get()),
@@ -343,10 +343,10 @@ impl PaintWorkletGlobalScope {
         ];
         let args = unsafe { HandleValueArray::from_rooted_slice(&args_slice) };
 
-        rooted!(in(cx) let mut result = UndefinedValue());
+        rooted!(in(*cx) let mut result = UndefinedValue());
         unsafe {
             Call(
-                cx,
+                *cx,
                 paint_instance.handle(),
                 paint_function.handle(),
                 &args,
@@ -356,10 +356,10 @@ impl PaintWorkletGlobalScope {
         let missing_image_urls = rendering_context.take_missing_image_urls();
 
         // Step 13.
-        if unsafe { JS_IsExceptionPending(cx) } {
+        if unsafe { JS_IsExceptionPending(*cx) } {
             debug!("Paint function threw an exception {}.", name);
             unsafe {
-                JS_ClearPendingException(cx);
+                JS_ClearPendingException(*cx);
             }
             return self.invalid_image(size_in_dpx, missing_image_urls);
         }
@@ -518,8 +518,8 @@ impl PaintWorkletGlobalScopeMethods for PaintWorkletGlobalScope {
     fn RegisterPaint(&self, name: DOMString, paint_ctor: Rc<VoidFunction>) -> Fallible<()> {
         let name = Atom::from(name);
         let cx = self.worklet_global.get_cx();
-        rooted!(in(cx) let paint_obj = paint_ctor.callback_holder().get());
-        rooted!(in(cx) let paint_val = ObjectValue(paint_obj.get()));
+        rooted!(in(*cx) let paint_obj = paint_ctor.callback_holder().get());
+        rooted!(in(*cx) let paint_val = ObjectValue(paint_obj.get()));
 
         debug!("Registering paint image name {}.", name);
 
@@ -535,20 +535,20 @@ impl PaintWorkletGlobalScopeMethods for PaintWorkletGlobalScope {
 
         // Step 4-6.
         let mut property_names: Vec<String> =
-            unsafe { get_property(cx, paint_obj.handle(), "inputProperties", ()) }?
+            unsafe { get_property(*cx, paint_obj.handle(), "inputProperties", ()) }?
                 .unwrap_or_default();
         let properties = property_names.drain(..).map(Atom::from).collect();
 
         // Step 7-9.
         let input_arguments: Vec<String> =
-            unsafe { get_property(cx, paint_obj.handle(), "inputArguments", ()) }?
+            unsafe { get_property(*cx, paint_obj.handle(), "inputArguments", ()) }?
                 .unwrap_or_default();
 
         // TODO: Steps 10-11.
 
         // Steps 12-13.
         let alpha: bool =
-            unsafe { get_property(cx, paint_obj.handle(), "alpha", ()) }?.unwrap_or(true);
+            unsafe { get_property(*cx, paint_obj.handle(), "alpha", ()) }?.unwrap_or(true);
 
         // Step 14
         if unsafe { !IsConstructor(paint_obj.get()) } {
@@ -556,19 +556,24 @@ impl PaintWorkletGlobalScopeMethods for PaintWorkletGlobalScope {
         }
 
         // Steps 15-16
-        rooted!(in(cx) let mut prototype = UndefinedValue());
+        rooted!(in(*cx) let mut prototype = UndefinedValue());
         unsafe {
-            get_property_jsval(cx, paint_obj.handle(), "prototype", prototype.handle_mut())?;
+            get_property_jsval(*cx, paint_obj.handle(), "prototype", prototype.handle_mut())?;
         }
         if !prototype.is_object() {
             return Err(Error::Type(String::from("Prototype is not an object.")));
         }
-        rooted!(in(cx) let prototype = prototype.to_object());
+        rooted!(in(*cx) let prototype = prototype.to_object());
 
         // Steps 17-18
-        rooted!(in(cx) let mut paint_function = UndefinedValue());
+        rooted!(in(*cx) let mut paint_function = UndefinedValue());
         unsafe {
-            get_property_jsval(cx, prototype.handle(), "paint", paint_function.handle_mut())?;
+            get_property_jsval(
+                *cx,
+                prototype.handle(),
+                "paint",
+                paint_function.handle_mut(),
+            )?;
         }
         if !paint_function.is_object() || unsafe { !IsCallable(paint_function.to_object()) } {
             return Err(Error::Type(String::from("Paint function is not callable.")));
diff --git a/components/script/dom/promise.rs b/components/script/dom/promise.rs
index fc1e39406f0..4dd6f53e711 100644
--- a/components/script/dom/promise.rs
+++ b/components/script/dom/promise.rs
@@ -89,17 +89,17 @@ impl Promise {
     #[allow(unsafe_code)]
     pub fn new_in_current_compartment(global: &GlobalScope, _comp: InCompartment) -> Rc<Promise> {
         let cx = global.get_cx();
-        rooted!(in(cx) let mut obj = ptr::null_mut::<JSObject>());
+        rooted!(in(*cx) let mut obj = ptr::null_mut::<JSObject>());
         unsafe {
-            Promise::create_js_promise(cx, HandleObject::null(), obj.handle_mut());
-            Promise::new_with_js_promise(obj.handle(), cx)
+            Promise::create_js_promise(*cx, HandleObject::null(), obj.handle_mut());
+            Promise::new_with_js_promise(obj.handle(), *cx)
         }
     }
 
     #[allow(unsafe_code)]
     pub fn duplicate(&self) -> Rc<Promise> {
         let cx = self.global().get_cx();
-        unsafe { Promise::new_with_js_promise(self.reflector().get_jsobject(), cx) }
+        unsafe { Promise::new_with_js_promise(self.reflector().get_jsobject(), *cx) }
     }
 
     #[allow(unsafe_code, unrooted_must_root)]
@@ -166,10 +166,10 @@ impl Promise {
     {
         let cx = self.global().get_cx();
         let _ac = enter_realm(&*self);
-        rooted!(in(cx) let mut v = UndefinedValue());
+        rooted!(in(*cx) let mut v = UndefinedValue());
         unsafe {
-            val.to_jsval(cx, v.handle_mut());
-            self.resolve(cx, v.handle());
+            val.to_jsval(*cx, v.handle_mut());
+            self.resolve(*cx, v.handle());
         }
     }
 
@@ -187,10 +187,10 @@ impl Promise {
     {
         let cx = self.global().get_cx();
         let _ac = enter_realm(&*self);
-        rooted!(in(cx) let mut v = UndefinedValue());
+        rooted!(in(*cx) let mut v = UndefinedValue());
         unsafe {
-            val.to_jsval(cx, v.handle_mut());
-            self.reject(cx, v.handle());
+            val.to_jsval(*cx, v.handle_mut());
+            self.reject(*cx, v.handle());
         }
     }
 
@@ -198,10 +198,10 @@ impl Promise {
     pub fn reject_error(&self, error: Error) {
         let cx = self.global().get_cx();
         let _ac = enter_realm(&*self);
-        rooted!(in(cx) let mut v = UndefinedValue());
+        rooted!(in(*cx) let mut v = UndefinedValue());
         unsafe {
-            error.to_jsval(cx, &self.global(), v.handle_mut());
-            self.reject(cx, v.handle());
+            error.to_jsval(*cx, &self.global(), v.handle_mut());
+            self.reject(*cx, v.handle());
         }
     }
 
@@ -233,19 +233,19 @@ impl Promise {
     #[allow(unsafe_code)]
     pub fn append_native_handler(&self, handler: &PromiseNativeHandler) {
         let cx = self.global().get_cx();
-        rooted!(in(cx) let resolve_func =
-                create_native_handler_function(cx,
+        rooted!(in(*cx) let resolve_func =
+                create_native_handler_function(*cx,
                                                handler.reflector().get_jsobject(),
                                                NativeHandlerTask::Resolve));
 
-        rooted!(in(cx) let reject_func =
-                create_native_handler_function(cx,
+        rooted!(in(*cx) let reject_func =
+                create_native_handler_function(*cx,
                                                handler.reflector().get_jsobject(),
                                                NativeHandlerTask::Reject));
 
         unsafe {
             let ok = AddPromiseReactions(
-                cx,
+                *cx,
                 self.promise_obj(),
                 resolve_func.handle(),
                 reject_func.handle(),
diff --git a/components/script/dom/serviceworkerglobalscope.rs b/components/script/dom/serviceworkerglobalscope.rs
index b88d4d054e1..5af7f07ab0f 100644
--- a/components/script/dom/serviceworkerglobalscope.rs
+++ b/components/script/dom/serviceworkerglobalscope.rs
@@ -337,7 +337,7 @@ impl ServiceWorkerGlobalScope {
 
                 unsafe {
                     // Handle interrupt requests
-                    JS_AddInterruptCallback(scope.get_cx(), Some(interrupt_callback));
+                    JS_AddInterruptCallback(*scope.get_cx(), Some(interrupt_callback));
                 }
 
                 scope.execute_script(DOMString::from(source));
@@ -413,7 +413,7 @@ impl ServiceWorkerGlobalScope {
                 let scope = self.upcast::<WorkerGlobalScope>();
                 let target = self.upcast();
                 let _ac = enter_realm(&*scope);
-                rooted!(in(scope.get_cx()) let mut message = UndefinedValue());
+                rooted!(in(*scope.get_cx()) let mut message = UndefinedValue());
                 data.read(scope.upcast(), message.handle_mut());
                 ExtendableMessageEvent::dispatch_jsval(target, scope.upcast(), message.handle());
             },
diff --git a/components/script/dom/userscripts.rs b/components/script/dom/userscripts.rs
index af7c2b6d3f1..4e9cc59d27f 100644
--- a/components/script/dom/userscripts.rs
+++ b/components/script/dom/userscripts.rs
@@ -22,7 +22,7 @@ pub fn load_script(head: &HTMLHeadElement) {
     doc.add_delayed_task(task!(UserScriptExecute: move || {
         let win = win.root();
         let cx = win.get_cx();
-        rooted!(in(cx) let mut rval = UndefinedValue());
+        rooted!(in(*cx) let mut rval = UndefinedValue());
 
         let path = PathBuf::from(&path_str);
         let mut files = read_dir(&path)
diff --git a/components/script/dom/vreyeparameters.rs b/components/script/dom/vreyeparameters.rs
index 0a8260610e1..a7463c34a28 100644
--- a/components/script/dom/vreyeparameters.rs
+++ b/components/script/dom/vreyeparameters.rs
@@ -45,10 +45,10 @@ impl VREyeParameters {
         let fov = VRFieldOfView::new(&global, parameters.field_of_view.clone());
 
         let cx = global.get_cx();
-        rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
+        rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
         unsafe {
             let _ = Float32Array::create(
-                cx,
+                *cx,
                 CreateWith::Slice(&parameters.offset),
                 array.handle_mut(),
             );
diff --git a/components/script/dom/vrframedata.rs b/components/script/dom/vrframedata.rs
index 9cfcadd96a8..b7b8c743080 100644
--- a/components/script/dom/vrframedata.rs
+++ b/components/script/dom/vrframedata.rs
@@ -62,7 +62,7 @@ impl VRFrameData {
             global,
             VRFrameDataBinding::Wrap,
         );
-        let cx = unsafe { JSContext::from_ptr(global.get_cx()) };
+        let cx = global.get_cx();
         create_typed_array(cx, &matrix, &root.left_proj);
         create_typed_array(cx, &matrix, &root.left_view);
         create_typed_array(cx, &matrix, &root.right_proj);
@@ -90,7 +90,7 @@ impl VRFrameData {
     #[allow(unsafe_code)]
     pub fn update(&self, data: &WebVRFrameData) {
         unsafe {
-            let cx = JSContext::from_ptr(self.global().get_cx());
+            let cx = self.global().get_cx();
             typedarray!(in(*cx) let left_proj_array: Float32Array = self.left_proj.get());
             if let Ok(mut array) = left_proj_array {
                 array.update(&data.left_projection_matrix);
diff --git a/components/script/dom/vrpose.rs b/components/script/dom/vrpose.rs
index 898691a9679..2303641d6eb 100644
--- a/components/script/dom/vrpose.rs
+++ b/components/script/dom/vrpose.rs
@@ -7,9 +7,9 @@ use crate::dom::bindings::codegen::Bindings::VRPoseBinding::VRPoseMethods;
 use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
 use crate::dom::bindings::root::DomRoot;
 use crate::dom::globalscope::GlobalScope;
-use crate::script_runtime::JSContext as SafeJSContext;
+use crate::script_runtime::JSContext;
 use dom_struct::dom_struct;
-use js::jsapi::{Heap, JSContext, JSObject};
+use js::jsapi::{Heap, JSObject};
 use js::typedarray::{CreateWith, Float32Array};
 use std::ptr;
 use std::ptr::NonNull;
@@ -33,21 +33,19 @@ pub struct VRPose {
 }
 
 #[allow(unsafe_code)]
-unsafe fn update_or_create_typed_array(
-    cx: *mut JSContext,
-    src: Option<&[f32]>,
-    dst: &Heap<*mut JSObject>,
-) {
+fn update_or_create_typed_array(cx: JSContext, src: Option<&[f32]>, dst: &Heap<*mut JSObject>) {
     match src {
         Some(data) => {
             if dst.get().is_null() {
-                rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
-                let _ = Float32Array::create(cx, CreateWith::Slice(data), array.handle_mut());
+                rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
+                let _ = unsafe {
+                    Float32Array::create(*cx, CreateWith::Slice(data), array.handle_mut())
+                };
                 (*dst).set(array.get());
             } else {
-                typedarray!(in(cx) let array: Float32Array = dst.get());
+                typedarray!(in(*cx) let array: Float32Array = dst.get());
                 if let Ok(mut array) = array {
-                    array.update(data);
+                    unsafe { array.update(data) };
                 }
             }
         },
@@ -96,69 +94,63 @@ impl VRPose {
     #[allow(unsafe_code)]
     pub fn update(&self, pose: &webvr::VRPose) {
         let cx = self.global().get_cx();
-        unsafe {
-            update_or_create_typed_array(
-                cx,
-                pose.position.as_ref().map(|v| &v[..]),
-                &self.position,
-            );
-            update_or_create_typed_array(
-                cx,
-                pose.orientation.as_ref().map(|v| &v[..]),
-                &self.orientation,
-            );
-            update_or_create_typed_array(
-                cx,
-                pose.linear_velocity.as_ref().map(|v| &v[..]),
-                &self.linear_vel,
-            );
-            update_or_create_typed_array(
-                cx,
-                pose.angular_velocity.as_ref().map(|v| &v[..]),
-                &self.angular_vel,
-            );
-            update_or_create_typed_array(
-                cx,
-                pose.linear_acceleration.as_ref().map(|v| &v[..]),
-                &self.linear_acc,
-            );
-            update_or_create_typed_array(
-                cx,
-                pose.angular_acceleration.as_ref().map(|v| &v[..]),
-                &self.angular_acc,
-            );
-        }
+        update_or_create_typed_array(cx, pose.position.as_ref().map(|v| &v[..]), &self.position);
+        update_or_create_typed_array(
+            cx,
+            pose.orientation.as_ref().map(|v| &v[..]),
+            &self.orientation,
+        );
+        update_or_create_typed_array(
+            cx,
+            pose.linear_velocity.as_ref().map(|v| &v[..]),
+            &self.linear_vel,
+        );
+        update_or_create_typed_array(
+            cx,
+            pose.angular_velocity.as_ref().map(|v| &v[..]),
+            &self.angular_vel,
+        );
+        update_or_create_typed_array(
+            cx,
+            pose.linear_acceleration.as_ref().map(|v| &v[..]),
+            &self.linear_acc,
+        );
+        update_or_create_typed_array(
+            cx,
+            pose.angular_acceleration.as_ref().map(|v| &v[..]),
+            &self.angular_acc,
+        );
     }
 }
 
 impl VRPoseMethods for VRPose {
     // https://w3c.github.io/webvr/#dom-vrpose-position
-    fn GetPosition(&self, _cx: SafeJSContext) -> Option<NonNull<JSObject>> {
+    fn GetPosition(&self, _cx: JSContext) -> Option<NonNull<JSObject>> {
         heap_to_option(&self.position)
     }
 
     // https://w3c.github.io/webvr/#dom-vrpose-linearvelocity
-    fn GetLinearVelocity(&self, _cx: SafeJSContext) -> Option<NonNull<JSObject>> {
+    fn GetLinearVelocity(&self, _cx: JSContext) -> Option<NonNull<JSObject>> {
         heap_to_option(&self.linear_vel)
     }
 
     // https://w3c.github.io/webvr/#dom-vrpose-linearacceleration
-    fn GetLinearAcceleration(&self, _cx: SafeJSContext) -> Option<NonNull<JSObject>> {
+    fn GetLinearAcceleration(&self, _cx: JSContext) -> Option<NonNull<JSObject>> {
         heap_to_option(&self.linear_acc)
     }
 
     // https://w3c.github.io/webvr/#dom-vrpose-orientation
-    fn GetOrientation(&self, _cx: SafeJSContext) -> Option<NonNull<JSObject>> {
+    fn GetOrientation(&self, _cx: JSContext) -> Option<NonNull<JSObject>> {
         heap_to_option(&self.orientation)
     }
 
     // https://w3c.github.io/webvr/#dom-vrpose-angularvelocity
-    fn GetAngularVelocity(&self, _cx: SafeJSContext) -> Option<NonNull<JSObject>> {
+    fn GetAngularVelocity(&self, _cx: JSContext) -> Option<NonNull<JSObject>> {
         heap_to_option(&self.angular_vel)
     }
 
     // https://w3c.github.io/webvr/#dom-vrpose-angularacceleration
-    fn GetAngularAcceleration(&self, _cx: SafeJSContext) -> Option<NonNull<JSObject>> {
+    fn GetAngularAcceleration(&self, _cx: JSContext) -> Option<NonNull<JSObject>> {
         heap_to_option(&self.angular_acc)
     }
 }
diff --git a/components/script/dom/vrstageparameters.rs b/components/script/dom/vrstageparameters.rs
index 0b525513f57..747608763e9 100644
--- a/components/script/dom/vrstageparameters.rs
+++ b/components/script/dom/vrstageparameters.rs
@@ -43,10 +43,10 @@ impl VRStageParameters {
         global: &GlobalScope,
     ) -> DomRoot<VRStageParameters> {
         let cx = global.get_cx();
-        rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
+        rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
         unsafe {
             let _ = Float32Array::create(
-                cx,
+                *cx,
                 CreateWith::Slice(&parameters.sitting_to_standing_transform),
                 array.handle_mut(),
             );
@@ -67,7 +67,7 @@ impl VRStageParameters {
     pub fn update(&self, parameters: &WebVRStageParameters) {
         unsafe {
             let cx = self.global().get_cx();
-            typedarray!(in(cx) let array: Float32Array = self.transform.get());
+            typedarray!(in(*cx) let array: Float32Array = self.transform.get());
             if let Ok(mut array) = array {
                 array.update(&parameters.sitting_to_standing_transform);
             }
diff --git a/components/script/dom/websocket.rs b/components/script/dom/websocket.rs
index 5f783ab5a30..3051cc0ff33 100644
--- a/components/script/dom/websocket.rs
+++ b/components/script/dom/websocket.rs
@@ -569,26 +569,26 @@ impl TaskOnce for MessageReceivedTask {
         // global.get_cx() returns a valid `JSContext` pointer, so this is safe.
         unsafe {
             let cx = global.get_cx();
-            let _ac = JSAutoRealm::new(cx, ws.reflector().get_jsobject().get());
-            rooted!(in(cx) let mut message = UndefinedValue());
+            let _ac = JSAutoRealm::new(*cx, ws.reflector().get_jsobject().get());
+            rooted!(in(*cx) let mut message = UndefinedValue());
             match self.message {
-                MessageData::Text(text) => text.to_jsval(cx, message.handle_mut()),
+                MessageData::Text(text) => text.to_jsval(*cx, message.handle_mut()),
                 MessageData::Binary(data) => match ws.binary_type.get() {
                     BinaryType::Blob => {
                         let blob =
                             Blob::new(&global, BlobImpl::new_from_bytes(data), "".to_owned());
-                        blob.to_jsval(cx, message.handle_mut());
+                        blob.to_jsval(*cx, message.handle_mut());
                     },
                     BinaryType::Arraybuffer => {
-                        rooted!(in(cx) let mut array_buffer = ptr::null_mut::<JSObject>());
+                        rooted!(in(*cx) let mut array_buffer = ptr::null_mut::<JSObject>());
                         assert!(ArrayBuffer::create(
-                            cx,
+                            *cx,
                             CreateWith::Slice(&data),
                             array_buffer.handle_mut()
                         )
                         .is_ok());
 
-                        (*array_buffer).to_jsval(cx, message.handle_mut());
+                        (*array_buffer).to_jsval(*cx, message.handle_mut());
                     },
                 },
             }
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index c97a3fd08fb..ccbd08e1ef7 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -57,8 +57,7 @@ use crate::fetch;
 use crate::layout_image::fetch_image_for_layout;
 use crate::microtask::MicrotaskQueue;
 use crate::script_runtime::{
-    CommonScriptMsg, JSContext as SafeJSContext, Runtime, ScriptChan, ScriptPort,
-    ScriptThreadEventCategory,
+    CommonScriptMsg, JSContext, Runtime, ScriptChan, ScriptPort, ScriptThreadEventCategory,
 };
 use crate::script_thread::{ImageCacheMsg, MainThreadScriptChan, MainThreadScriptMsg};
 use crate::script_thread::{ScriptThread, SendableMainThreadScriptChan};
@@ -80,7 +79,6 @@ use euclid::{Point2D, Rect, Scale, Size2D, Vector2D};
 use ipc_channel::ipc::{channel, IpcSender};
 use ipc_channel::router::ROUTER;
 use js::jsapi::JSAutoRealm;
-use js::jsapi::JSContext;
 use js::jsapi::JSPROP_ENUMERATE;
 use js::jsapi::{GCReason, JS_GC};
 use js::jsval::JSVal;
@@ -372,8 +370,9 @@ impl Window {
         self.globalscope.origin()
     }
 
-    pub fn get_cx(&self) -> *mut JSContext {
-        self.js_runtime.borrow().as_ref().unwrap().cx()
+    #[allow(unsafe_code)]
+    pub fn get_cx(&self) -> JSContext {
+        unsafe { JSContext::from_ptr(self.js_runtime.borrow().as_ref().unwrap().cx()) }
     }
 
     pub fn main_thread_script_chan(&self) -> &Sender<MainThreadScriptMsg> {
@@ -615,13 +614,13 @@ impl WindowMethods for Window {
 
     #[allow(unsafe_code)]
     // https://html.spec.whatwg.org/multipage/#dom-opener
-    fn Opener(&self, cx: SafeJSContext) -> JSVal {
+    fn Opener(&self, cx: JSContext) -> JSVal {
         unsafe { self.window_proxy().opener(*cx) }
     }
 
     #[allow(unsafe_code)]
     // https://html.spec.whatwg.org/multipage/#dom-opener
-    fn SetOpener(&self, cx: SafeJSContext, value: HandleValue) {
+    fn SetOpener(&self, cx: JSContext, value: HandleValue) {
         // Step 1.
         if value.is_null() {
             return self.window_proxy().disown();
@@ -744,7 +743,7 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-windowtimers-settimeout
     fn SetTimeout(
         &self,
-        _cx: SafeJSContext,
+        _cx: JSContext,
         callback: Rc<Function>,
         timeout: i32,
         args: Vec<HandleValue>,
@@ -760,7 +759,7 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-windowtimers-settimeout
     fn SetTimeout_(
         &self,
-        _cx: SafeJSContext,
+        _cx: JSContext,
         callback: DOMString,
         timeout: i32,
         args: Vec<HandleValue>,
@@ -782,7 +781,7 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-windowtimers-setinterval
     fn SetInterval(
         &self,
-        _cx: SafeJSContext,
+        _cx: JSContext,
         callback: Rc<Function>,
         timeout: i32,
         args: Vec<HandleValue>,
@@ -798,7 +797,7 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-windowtimers-setinterval
     fn SetInterval_(
         &self,
-        _cx: SafeJSContext,
+        _cx: JSContext,
         callback: DOMString,
         timeout: i32,
         args: Vec<HandleValue>,
@@ -902,12 +901,7 @@ impl WindowMethods for Window {
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-window-postmessage
-    fn PostMessage(
-        &self,
-        cx: SafeJSContext,
-        message: HandleValue,
-        origin: DOMString,
-    ) -> ErrorResult {
+    fn PostMessage(&self, cx: JSContext, message: HandleValue, origin: DOMString) -> ErrorResult {
         let source_global = GlobalScope::incumbent().expect("no incumbent global??");
         let source = source_global.as_window();
 
@@ -948,7 +942,7 @@ impl WindowMethods for Window {
     #[allow(unsafe_code)]
     fn Gc(&self) {
         unsafe {
-            JS_GC(self.get_cx(), GCReason::API);
+            JS_GC(*self.get_cx(), GCReason::API);
         }
     }
 
@@ -958,7 +952,7 @@ impl WindowMethods for Window {
     }
 
     #[allow(unsafe_code)]
-    fn WebdriverCallback(&self, cx: SafeJSContext, val: HandleValue) {
+    fn WebdriverCallback(&self, cx: JSContext, val: HandleValue) {
         let rv = unsafe { jsval_to_webdriver(*cx, val) };
         let opt_chan = self.webdriver_script_chan.borrow_mut().take();
         if let Some(chan) = opt_chan {
@@ -2177,7 +2171,7 @@ impl Window {
             player_context,
         });
 
-        unsafe { WindowBinding::Wrap(SafeJSContext::from_ptr(runtime.cx()), win) }
+        unsafe { WindowBinding::Wrap(JSContext::from_ptr(runtime.cx()), win) }
     }
 
     pub fn pipeline_id(&self) -> Option<PipelineId> {
@@ -2279,8 +2273,8 @@ impl Window {
             // Steps 7.2.-7.5.
             let cx = this.get_cx();
             let obj = this.reflector().get_jsobject();
-            let _ac = JSAutoRealm::new(cx, obj.get());
-            rooted!(in(cx) let mut message_clone = UndefinedValue());
+            let _ac = JSAutoRealm::new(*cx, obj.get());
+            rooted!(in(*cx) let mut message_clone = UndefinedValue());
             serialize_with_transfer_result.read(
                 this.upcast(),
                 message_clone.handle_mut(),
diff --git a/components/script/dom/windowproxy.rs b/components/script/dom/windowproxy.rs
index d527a73c86f..0c7a00978bc 100644
--- a/components/script/dom/windowproxy.rs
+++ b/components/script/dom/windowproxy.rs
@@ -152,10 +152,10 @@ impl WindowProxy {
                 ((*get_object_class(window_jsobject.get())).flags & JSCLASS_IS_GLOBAL),
                 0
             );
-            let _ac = JSAutoRealm::new(cx, window_jsobject.get());
+            let _ac = JSAutoRealm::new(*cx, window_jsobject.get());
 
             // Create a new window proxy.
-            rooted!(in(cx) let js_proxy = NewWindowProxy(cx, window_jsobject, handler));
+            rooted!(in(*cx) let js_proxy = NewWindowProxy(*cx, window_jsobject, handler));
             assert!(!js_proxy.is_null());
 
             // Create a new browsing context.
@@ -178,7 +178,7 @@ impl WindowProxy {
             );
 
             // Notify the JS engine about the new window proxy binding.
-            SetWindowProxy(cx, window_jsobject, js_proxy.handle());
+            SetWindowProxy(*cx, window_jsobject, js_proxy.handle());
 
             // Set the reflector.
             debug!(
@@ -223,10 +223,10 @@ impl WindowProxy {
                 ((*get_object_class(window_jsobject.get())).flags & JSCLASS_IS_GLOBAL),
                 0
             );
-            let _ac = JSAutoRealm::new(cx, window_jsobject.get());
+            let _ac = JSAutoRealm::new(*cx, window_jsobject.get());
 
             // Create a new window proxy.
-            rooted!(in(cx) let js_proxy = NewWindowProxy(cx, window_jsobject, handler));
+            rooted!(in(*cx) let js_proxy = NewWindowProxy(*cx, window_jsobject, handler));
             assert!(!js_proxy.is_null());
 
             // The window proxy owns the browsing context.
@@ -238,7 +238,7 @@ impl WindowProxy {
             );
 
             // Notify the JS engine about the new window proxy binding.
-            SetWindowProxy(cx, window_jsobject, js_proxy.handle());
+            SetWindowProxy(*cx, window_jsobject, js_proxy.handle());
 
             // Set the reflector.
             debug!(
@@ -576,20 +576,20 @@ impl WindowProxy {
             // of the old window proxy to the new window proxy, then
             // making the old window proxy a cross-compartment wrapper
             // pointing to the new window proxy.
-            rooted!(in(cx) let new_js_proxy = NewWindowProxy(cx, window_jsobject, handler));
+            rooted!(in(*cx) let new_js_proxy = NewWindowProxy(*cx, window_jsobject, handler));
             debug!(
                 "Transplanting proxy from {:p} to {:p}.",
                 old_js_proxy.get(),
                 new_js_proxy.get()
             );
-            rooted!(in(cx) let new_js_proxy = JS_TransplantObject(cx, old_js_proxy, new_js_proxy.handle()));
+            rooted!(in(*cx) let new_js_proxy = JS_TransplantObject(*cx, old_js_proxy, new_js_proxy.handle()));
             debug!("Transplanted proxy is {:p}.", new_js_proxy.get());
 
             // Transfer ownership of this browsing context from the old window proxy to the new one.
             SetProxyReservedSlot(new_js_proxy.get(), 0, &PrivateValue(self.as_void_ptr()));
 
             // Notify the JS engine about the new window proxy binding.
-            SetWindowProxy(cx, window_jsobject, new_js_proxy.handle());
+            SetWindowProxy(*cx, window_jsobject, new_js_proxy.handle());
 
             // Update the reflector.
             debug!(
diff --git a/components/script/dom/worker.rs b/components/script/dom/worker.rs
index 4b8384e3ed8..1ae17571fbb 100644
--- a/components/script/dom/worker.rs
+++ b/components/script/dom/worker.rs
@@ -147,7 +147,7 @@ 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(*global.get_cx()) let mut message = UndefinedValue());
         data.read(&global, message.handle_mut());
         MessageEvent::dispatch_jsval(target, &global, message.handle(), None, None);
     }
@@ -186,7 +186,7 @@ impl WorkerMethods for Worker {
 
         // Step 3
         let cx = self.global().get_cx();
-        unsafe { JS_RequestInterruptCallback(cx) };
+        unsafe { JS_RequestInterruptCallback(*cx) };
     }
 
     // https://html.spec.whatwg.org/multipage/#handler-worker-onmessage
diff --git a/components/script/dom/workerglobalscope.rs b/components/script/dom/workerglobalscope.rs
index bf21b8442c3..2e5a199a08f 100644
--- a/components/script/dom/workerglobalscope.rs
+++ b/components/script/dom/workerglobalscope.rs
@@ -26,7 +26,7 @@ use crate::dom::window::{base64_atob, base64_btoa};
 use crate::dom::workerlocation::WorkerLocation;
 use crate::dom::workernavigator::WorkerNavigator;
 use crate::fetch;
-use crate::script_runtime::JSContext as SafeJSContext;
+use crate::script_runtime::JSContext;
 use crate::script_runtime::{get_reports, CommonScriptMsg, Runtime, ScriptChan, ScriptPort};
 use crate::task::TaskCanceller;
 use crate::task_source::dom_manipulation::DOMManipulationTaskSource;
@@ -40,7 +40,7 @@ use crossbeam_channel::Receiver;
 use devtools_traits::{DevtoolScriptControlMsg, WorkerId};
 use dom_struct::dom_struct;
 use ipc_channel::ipc::IpcSender;
-use js::jsapi::{JSAutoRealm, JSContext};
+use js::jsapi::JSAutoRealm;
 use js::jsval::UndefinedValue;
 use js::panic::maybe_resume_unwind;
 use js::rust::{HandleValue, ParentRuntime};
@@ -165,8 +165,9 @@ impl WorkerGlobalScope {
         &self.from_devtools_receiver
     }
 
-    pub fn get_cx(&self) -> *mut JSContext {
-        self.runtime.cx()
+    #[allow(unsafe_code)]
+    pub fn get_cx(&self) -> JSContext {
+        unsafe { JSContext::from_ptr(self.runtime.cx()) }
     }
 
     pub fn is_closing(&self) -> bool {
@@ -292,7 +293,7 @@ impl WorkerGlobalScopeMethods for WorkerGlobalScope {
     // https://html.spec.whatwg.org/multipage/#dom-windowtimers-settimeout
     fn SetTimeout(
         &self,
-        _cx: SafeJSContext,
+        _cx: JSContext,
         callback: Rc<Function>,
         timeout: i32,
         args: Vec<HandleValue>,
@@ -308,7 +309,7 @@ impl WorkerGlobalScopeMethods for WorkerGlobalScope {
     // https://html.spec.whatwg.org/multipage/#dom-windowtimers-settimeout
     fn SetTimeout_(
         &self,
-        _cx: SafeJSContext,
+        _cx: JSContext,
         callback: DOMString,
         timeout: i32,
         args: Vec<HandleValue>,
@@ -330,7 +331,7 @@ impl WorkerGlobalScopeMethods for WorkerGlobalScope {
     // https://html.spec.whatwg.org/multipage/#dom-windowtimers-setinterval
     fn SetInterval(
         &self,
-        _cx: SafeJSContext,
+        _cx: JSContext,
         callback: Rc<Function>,
         timeout: i32,
         args: Vec<HandleValue>,
@@ -346,7 +347,7 @@ impl WorkerGlobalScopeMethods for WorkerGlobalScope {
     // https://html.spec.whatwg.org/multipage/#dom-windowtimers-setinterval
     fn SetInterval_(
         &self,
-        _cx: SafeJSContext,
+        _cx: JSContext,
         callback: DOMString,
         timeout: i32,
         args: Vec<HandleValue>,
@@ -477,7 +478,7 @@ impl WorkerGlobalScope {
             CommonScriptMsg::CollectReports(reports_chan) => {
                 let cx = self.get_cx();
                 let path_seg = format!("url({})", self.get_url());
-                let reports = get_reports(cx, path_seg);
+                let reports = get_reports(*cx, path_seg);
                 reports_chan.send(reports);
             },
         }
diff --git a/components/script/dom/workletglobalscope.rs b/components/script/dom/workletglobalscope.rs
index 20f99c76ee2..90fa5bd0115 100644
--- a/components/script/dom/workletglobalscope.rs
+++ b/components/script/dom/workletglobalscope.rs
@@ -10,13 +10,13 @@ use crate::dom::paintworkletglobalscope::PaintWorkletTask;
 use crate::dom::testworkletglobalscope::TestWorkletGlobalScope;
 use crate::dom::testworkletglobalscope::TestWorkletTask;
 use crate::dom::worklet::WorkletExecutor;
+use crate::script_runtime::JSContext;
 use crate::script_thread::MainThreadScriptMsg;
 use crossbeam_channel::Sender;
 use devtools_traits::ScriptToDevtoolsControlMsg;
 use dom_struct::dom_struct;
 use ipc_channel::ipc;
 use ipc_channel::ipc::IpcSender;
-use js::jsapi::JSContext;
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
 use msg::constellation_msg::PipelineId;
@@ -83,14 +83,14 @@ impl WorkletGlobalScope {
     }
 
     /// Get the JS context.
-    pub fn get_cx(&self) -> *mut JSContext {
+    pub fn get_cx(&self) -> JSContext {
         self.globalscope.get_cx()
     }
 
     /// Evaluate a JS script in this global.
     pub fn evaluate_js(&self, script: &str) -> bool {
         debug!("Evaluating Dom.");
-        rooted!(in (self.globalscope.get_cx()) let mut rval = UndefinedValue());
+        rooted!(in (*self.globalscope.get_cx()) let mut rval = UndefinedValue());
         self.globalscope
             .evaluate_js_on_global_with_result(&*script, rval.handle_mut())
     }
diff --git a/components/script/dom/xrrigidtransform.rs b/components/script/dom/xrrigidtransform.rs
index b9690187494..2b09b89e096 100644
--- a/components/script/dom/xrrigidtransform.rs
+++ b/components/script/dom/xrrigidtransform.rs
@@ -119,10 +119,9 @@ impl XRRigidTransformMethods for XRRigidTransform {
         })
     }
     // https://immersive-web.github.io/webxr/#dom-xrrigidtransform-matrix
-    #[allow(unsafe_code)]
     fn Matrix(&self, _cx: JSContext) -> NonNull<JSObject> {
         if self.matrix.get().is_null() {
-            let cx = unsafe { JSContext::from_ptr(self.global().get_cx()) };
+            let cx = self.global().get_cx();
             // According to the spec all matrices are column-major,
             // however euclid uses row vectors so we use .to_row_major_array()
             let arr = self.transform.to_transform().to_row_major_array();
diff --git a/components/script/dom/xrview.rs b/components/script/dom/xrview.rs
index bc51d8f38c8..04a4a2b66c8 100644
--- a/components/script/dom/xrview.rs
+++ b/components/script/dom/xrview.rs
@@ -40,7 +40,6 @@ impl XRView {
         }
     }
 
-    #[allow(unsafe_code)]
     pub fn new<V: Copy>(
         global: &GlobalScope,
         session: &XRSession,
@@ -65,7 +64,7 @@ impl XRView {
 
         // row_major since euclid uses row vectors
         let proj = view.projection.to_row_major_array();
-        let cx = unsafe { JSContext::from_ptr(global.get_cx()) };
+        let cx = global.get_cx();
         create_typed_array(cx, &proj, &ret.proj);
         ret
     }
diff --git a/components/script/dom/xrviewerpose.rs b/components/script/dom/xrviewerpose.rs
index ce3f94c1817..8ebabc0781f 100644
--- a/components/script/dom/xrviewerpose.rs
+++ b/components/script/dom/xrviewerpose.rs
@@ -57,10 +57,10 @@ impl XRViewerPose {
             XRViewerPoseBinding::Wrap,
         );
 
+        let cx = global.get_cx();
         unsafe {
-            let cx = global.get_cx();
-            rooted!(in(cx) let mut jsval = UndefinedValue());
-            views.to_jsval(cx, jsval.handle_mut());
+            rooted!(in(*cx) let mut jsval = UndefinedValue());
+            views.to_jsval(*cx, jsval.handle_mut());
             pose.views.set(jsval.get());
         }
 
diff --git a/components/script/dom/xrwebgllayer.rs b/components/script/dom/xrwebgllayer.rs
index a5f06df0e52..148d773fe6f 100644
--- a/components/script/dom/xrwebgllayer.rs
+++ b/components/script/dom/xrwebgllayer.rs
@@ -115,7 +115,7 @@ impl XRWebGLLayer {
             0,
             constants::RGBA,
             constants::UNSIGNED_BYTE,
-            pixels.root(cx),
+            pixels.root(*cx),
         );
 
         // Bind the new texture to the framebuffer
diff --git a/components/script/script_runtime.rs b/components/script/script_runtime.rs
index 4c7953de443..fb94d30fafd 100644
--- a/components/script/script_runtime.rs
+++ b/components/script/script_runtime.rs
@@ -245,7 +245,7 @@ unsafe extern "C" fn promise_rejection_tracker(
                         let cx = target.global().get_cx();
                         let root_promise = trusted_promise.root();
 
-                        rooted!(in(cx) let reason = GetPromiseResult(root_promise.reflector().get_jsobject()));
+                        rooted!(in(*cx) let reason = GetPromiseResult(root_promise.reflector().get_jsobject()));
 
                         let event = PromiseRejectionEvent::new(
                             &target.global(),
@@ -270,9 +270,8 @@ 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();
     unsafe {
-        let cx = global.get_cx();
-
         // Step 2.
         if global.get_uncaught_rejections().borrow().len() > 0 {
             // Step 1.
@@ -282,7 +281,7 @@ pub fn notify_about_rejected_promises(global: &GlobalScope) {
                 .iter()
                 .map(|promise| {
                     let promise =
-                        Promise::new_with_js_promise(Handle::from_raw(promise.handle()), cx);
+                        Promise::new_with_js_promise(Handle::from_raw(promise.handle()), *cx);
 
                     TrustedPromise::new(promise)
                 })
@@ -309,7 +308,7 @@ pub fn notify_about_rejected_promises(global: &GlobalScope) {
                         }
 
                         // Step 4-2.
-                        rooted!(in(cx) let reason = GetPromiseResult(promise.reflector().get_jsobject()));
+                        rooted!(in(*cx) let reason = GetPromiseResult(promise.reflector().get_jsobject()));
 
                         let event = PromiseRejectionEvent::new(
                             &target.global(),
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 0ceed35db57..81ef7d9493c 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -70,7 +70,7 @@ use crate::dom::worklet::WorkletThreadPool;
 use crate::dom::workletglobalscope::WorkletGlobalScopeInit;
 use crate::fetch::FetchCanceller;
 use crate::microtask::{Microtask, MicrotaskQueue};
-use crate::script_runtime::{get_reports, new_rt_and_cx, Runtime, ScriptPort};
+use crate::script_runtime::{get_reports, new_rt_and_cx, JSContext, Runtime, ScriptPort};
 use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
 use crate::serviceworkerjob::{Job, JobQueue};
 use crate::task_manager::TaskManager;
@@ -102,7 +102,7 @@ use hyper_serde::Serde;
 use ipc_channel::ipc::{self, IpcSender};
 use ipc_channel::router::ROUTER;
 use js::glue::GetWindowProxyClass;
-use js::jsapi::{JSContext, JS_SetWrapObjectCallbacks};
+use js::jsapi::JS_SetWrapObjectCallbacks;
 use js::jsapi::{JSTracer, SetWindowProxyClass};
 use js::jsval::UndefinedValue;
 use js::rust::ParentRuntime;
@@ -915,7 +915,7 @@ impl ScriptThread {
                     let script_thread = &*script_thread;
                     script_thread
                         .microtask_queue
-                        .enqueue(task, script_thread.get_cx());
+                        .enqueue(task, *script_thread.get_cx());
                 }
             }
         });
@@ -1317,8 +1317,9 @@ impl ScriptThread {
         }
     }
 
-    pub fn get_cx(&self) -> *mut JSContext {
-        self.js_runtime.cx()
+    #[allow(unsafe_code)]
+    pub fn get_cx(&self) -> JSContext {
+        unsafe { JSContext::from_ptr(self.js_runtime.cx()) }
     }
 
     /// Starts the script thread. After calling this method, the script thread will loop receiving
@@ -2349,7 +2350,7 @@ impl ScriptThread {
         let path_seg = format!("url({})", urls);
 
         let mut reports = vec![];
-        reports.extend(get_reports(self.get_cx(), path_seg));
+        reports.extend(get_reports(*self.get_cx(), path_seg));
         reports_chan.send(reports);
     }
 
@@ -3540,13 +3541,13 @@ 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(*global_scope.get_cx()) let mut jsval = UndefinedValue());
         global_scope.evaluate_js_on_global_with_result(&script_source, jsval.handle_mut());
 
         load_data.js_eval_result = if jsval.get().is_string() {
             unsafe {
                 let strval = DOMString::from_jsval(
-                    global_scope.get_cx(),
+                    *global_scope.get_cx(),
                     jsval.handle(),
                     StringificationBehavior::Empty,
                 );
@@ -3776,7 +3777,7 @@ impl ScriptThread {
             let script_thread = &*root.get().unwrap();
             script_thread
                 .microtask_queue
-                .enqueue(job, script_thread.get_cx());
+                .enqueue(job, *script_thread.get_cx());
         });
     }
 
@@ -3791,7 +3792,7 @@ impl ScriptThread {
 
         unsafe {
             self.microtask_queue.checkpoint(
-                self.get_cx(),
+                *self.get_cx(),
                 |id| self.documents.borrow().find_global(id),
                 globals,
             )
diff --git a/components/script/timers.rs b/components/script/timers.rs
index 45c809394a1..5534df60d45 100644
--- a/components/script/timers.rs
+++ b/components/script/timers.rs
@@ -517,7 +517,7 @@ impl JsTimerTask {
             InternalTimerCallback::StringTimerCallback(ref code_str) => {
                 let global = this.global();
                 let cx = global.get_cx();
-                rooted!(in(cx) let mut rval = UndefinedValue());
+                rooted!(in(*cx) let mut rval = UndefinedValue());
 
                 global.evaluate_js_on_global_with_result(code_str, rval.handle_mut());
             },
diff --git a/components/script/webdriver_handlers.rs b/components/script/webdriver_handlers.rs
index ab08c0efe7d..c8aad9a6b4c 100644
--- a/components/script/webdriver_handlers.rs
+++ b/components/script/webdriver_handlers.rs
@@ -145,11 +145,11 @@ pub fn handle_execute_script(
         Some(window) => {
             let result = unsafe {
                 let cx = window.get_cx();
-                rooted!(in(cx) let mut rval = UndefinedValue());
+                rooted!(in(*cx) let mut rval = UndefinedValue());
                 window
                     .upcast::<GlobalScope>()
                     .evaluate_js_on_global_with_result(&eval, rval.handle_mut());
-                jsval_to_webdriver(cx, rval.handle())
+                jsval_to_webdriver(*cx, rval.handle())
             };
 
             reply.send(result).unwrap();
@@ -171,7 +171,7 @@ pub fn handle_execute_async_script(
         Some(window) => {
             let cx = window.get_cx();
             window.set_webdriver_script_chan(Some(reply));
-            rooted!(in(cx) let mut rval = UndefinedValue());
+            rooted!(in(*cx) let mut rval = UndefinedValue());
             window
                 .upcast::<GlobalScope>()
                 .evaluate_js_on_global_with_result(&eval, rval.handle_mut());
@@ -725,21 +725,21 @@ pub fn handle_get_property(
             Some(node) => {
                 let cx = documents.find_document(pipeline).unwrap().window().get_cx();
 
-                rooted!(in(cx) let mut property = UndefinedValue());
+                rooted!(in(*cx) let mut property = UndefinedValue());
                 match unsafe {
                     get_property_jsval(
-                        cx,
+                        *cx,
                         node.reflector().get_jsobject(),
                         &name,
                         property.handle_mut(),
                     )
                 } {
-                    Ok(_) => match unsafe { jsval_to_webdriver(cx, property.handle()) } {
+                    Ok(_) => match unsafe { jsval_to_webdriver(*cx, property.handle()) } {
                         Ok(property) => Ok(property),
                         Err(_) => Ok(WebDriverJSValue::Undefined),
                     },
                     Err(error) => {
-                        unsafe { throw_dom_exception(cx, &node.reflector().global(), error) };
+                        unsafe { throw_dom_exception(*cx, &node.reflector().global(), error) };
                         Ok(WebDriverJSValue::Undefined)
                     },
                 }