Fix tyvar_behind_raw_pointer warnings

https://github.com/rust-lang/rust/issues/46906

20 files changed, 55 insertions, 53 deletions

diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index 6f0dd003e8d..4a377aa351f 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -2539,7 +2539,7 @@ def CopyUnforgeablePropertiesToInstance(descriptor):
     # reflector, so we can make sure we don't get confused by named getters.
     if descriptor.proxy:
         copyCode += """\
-rooted!(in(cx) let mut expando = ptr::null_mut());
+rooted!(in(cx) let mut expando = ptr::null_mut::<JSObject>());
 ensure_expando_object(cx, obj.handle(), expando.handle_mut());
 """
         obj = "expando"
@@ -2554,7 +2554,7 @@ ensure_expando_object(cx, obj.handle(), expando.handle_mut());
     else:
         copyFunc = "JS_InitializePropertiesFromCompatibleNativeObject"
     copyCode += """\
-rooted!(in(cx) let mut unforgeable_holder = ptr::null_mut());
+rooted!(in(cx) let mut unforgeable_holder = ptr::null_mut::<JSObject>());
 unforgeable_holder.handle_mut().set(
     JS_GetReservedSlot(proto.get(), DOM_PROTO_UNFORGEABLE_HOLDER_SLOT).to_object());
 assert!(%(copyFunc)s(cx, %(obj)s.handle(), unforgeable_holder.handle()));
@@ -2586,7 +2586,7 @@ let scope = scope.reflector().get_jsobject();
 assert!(!scope.get().is_null());
 assert!(((*get_object_class(scope.get())).flags & JSCLASS_IS_GLOBAL) != 0);
 
-rooted!(in(cx) let mut proto = ptr::null_mut());
+rooted!(in(cx) let mut proto = ptr::null_mut::<JSObject>());
 let _ac = JSAutoCompartment::new(cx, scope.get());
 GetProtoObject(cx, scope, proto.handle_mut());
 assert!(!proto.is_null());
@@ -2631,7 +2631,7 @@ class CGWrapGlobalMethod(CGAbstractMethod):
 let raw = Box::into_raw(object);
 let _rt = RootedTraceable::new(&*raw);
 
-rooted!(in(cx) let mut obj = ptr::null_mut());
+rooted!(in(cx) let mut obj = ptr::null_mut::<JSObject>());
 create_global_object(
     cx,
     &Class.base,
@@ -2643,7 +2643,7 @@ assert!(!obj.is_null());
 (*raw).init_reflector(obj.get());
 
 let _ac = JSAutoCompartment::new(cx, obj.get());
-rooted!(in(cx) let mut proto = ptr::null_mut());
+rooted!(in(cx) let mut proto = ptr::null_mut::<JSObject>());
 GetProtoObject(cx, obj.handle(), proto.handle_mut());
 assert!(JS_SplicePrototype(cx, obj.handle(), proto.handle()));
 let mut immutable = false;
@@ -2771,7 +2771,7 @@ class CGCreateInterfaceObjectsMethod(CGAbstractMethod):
             return CGGeneric("""\
 rooted!(in(cx) let proto = %(proto)s);
 assert!(!proto.is_null());
-rooted!(in(cx) let mut namespace = ptr::null_mut());
+rooted!(in(cx) let mut namespace = ptr::null_mut::<JSObject>());
 create_namespace_object(cx, global, proto.handle(), &NAMESPACE_OBJECT_CLASS,
                         %(methods)s, %(name)s, namespace.handle_mut());
 assert!(!namespace.is_null());
@@ -2784,7 +2784,7 @@ assert!((*cache)[PrototypeList::Constructor::%(id)s as usize].is_null());
         if self.descriptor.interface.isCallback():
             assert not self.descriptor.interface.ctor() and self.descriptor.interface.hasConstants()
             return CGGeneric("""\
-rooted!(in(cx) let mut interface = ptr::null_mut());
+rooted!(in(cx) let mut interface = ptr::null_mut::<JSObject>());
 create_callback_interface_object(cx, global, sConstants, %(name)s, interface.handle_mut());
 assert!(!interface.is_null());
 assert!((*cache)[PrototypeList::Constructor::%(id)s as usize].is_null());
@@ -2807,7 +2807,7 @@ assert!((*cache)[PrototypeList::Constructor::%(id)s as usize].is_null());
                                  toBindingNamespace(parentName))
 
         code = [CGGeneric("""\
-rooted!(in(cx) let mut prototype_proto = ptr::null_mut());
+rooted!(in(cx) let mut prototype_proto = ptr::null_mut::<JSObject>());
 %s;
 assert!(!prototype_proto.is_null());""" % getPrototypeProto)]
 
@@ -2835,7 +2835,7 @@ assert!(!prototype_proto.is_null());""" % getPrototypeProto)]
             proto_properties = properties
 
         code.append(CGGeneric("""
-rooted!(in(cx) let mut prototype = ptr::null_mut());
+rooted!(in(cx) let mut prototype = ptr::null_mut::<JSObject>());
 create_interface_prototype_object(cx,
                                   prototype_proto.handle(),
                                   &PrototypeClass,
@@ -2862,7 +2862,7 @@ assert!((*cache)[PrototypeList::ID::%(id)s as usize].is_null());
             if parentName:
                 parentName = toBindingNamespace(parentName)
                 code.append(CGGeneric("""
-rooted!(in(cx) let mut interface_proto = ptr::null_mut());
+rooted!(in(cx) let mut interface_proto = ptr::null_mut::<JSObject>());
 %s::GetConstructorObject(cx, global, interface_proto.handle_mut());""" % parentName))
             else:
                 code.append(CGGeneric("""
@@ -2870,7 +2870,7 @@ rooted!(in(cx) let interface_proto = JS_GetFunctionPrototype(cx, global));"""))
             code.append(CGGeneric("""\
 assert!(!interface_proto.is_null());
 
-rooted!(in(cx) let mut interface = ptr::null_mut());
+rooted!(in(cx) let mut interface = ptr::null_mut::<JSObject>());
 create_noncallback_interface_object(cx,
                                     global,
                                     interface_proto.handle(),
@@ -2973,7 +2973,7 @@ assert!((*cache)[PrototypeList::Constructor::%(id)s as usize].is_null());
                 holderClass = "&Class.base as *const JSClass"
                 holderProto = "prototype.handle()"
             code.append(CGGeneric("""
-rooted!(in(cx) let mut unforgeable_holder = ptr::null_mut());
+rooted!(in(cx) let mut unforgeable_holder = ptr::null_mut::<JSObject>());
 unforgeable_holder.handle_mut().set(
     JS_NewObjectWithoutMetadata(cx, %(holderClass)s, %(holderProto)s));
 assert!(!unforgeable_holder.is_null());
@@ -3151,7 +3151,7 @@ if !ConstructorEnabled(cx, global) {
     return;
 }
 
-rooted!(in(cx) let mut proto = ptr::null_mut());
+rooted!(in(cx) let mut proto = ptr::null_mut::<JSObject>());
 %s(cx, global, proto.handle_mut());
 assert!(!proto.is_null());""" % (function,))
 
@@ -4941,7 +4941,7 @@ if %s {
 
         # FIXME(#11868) Should assign to desc.obj, desc.get() is a copy.
         return get + """\
-rooted!(in(cx) let mut expando = ptr::null_mut());
+rooted!(in(cx) let mut expando = ptr::null_mut::<JSObject>());
 get_expando_object(proxy, expando.handle_mut());
 //if (!xpc::WrapperFactory::IsXrayWrapper(proxy) && (expando = GetExpandoObject(proxy))) {
 if !expando.is_null() {
@@ -5071,7 +5071,7 @@ class CGDOMJSProxyHandler_ownPropertyKeys(CGAbstractExternMethod):
 
         body += dedent(
             """
-            rooted!(in(cx) let mut expando = ptr::null_mut());
+            rooted!(in(cx) let mut expando = ptr::null_mut::<JSObject>());
             get_expando_object(proxy, expando.handle_mut());
             if !expando.is_null() {
                 GetPropertyKeys(cx, expando.handle(), JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS, props);
@@ -5114,7 +5114,7 @@ class CGDOMJSProxyHandler_getOwnEnumerablePropertyKeys(CGAbstractExternMethod):
 
         body += dedent(
             """
-            rooted!(in(cx) let mut expando = ptr::null_mut());
+            rooted!(in(cx) let mut expando = ptr::null_mut::<JSObject>());
             get_expando_object(proxy, expando.handle_mut());
             if !expando.is_null() {
                 GetPropertyKeys(cx, expando.handle(), JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS, props);
@@ -5173,7 +5173,7 @@ if %s {
             named = ""
 
         return indexed + """\
-rooted!(in(cx) let mut expando = ptr::null_mut());
+rooted!(in(cx) let mut expando = ptr::null_mut::<JSObject>());
 get_expando_object(proxy, expando.handle_mut());
 if !expando.is_null() {
     let ok = JS_HasPropertyById(cx, expando.handle(), id, bp);
@@ -5200,7 +5200,7 @@ class CGDOMJSProxyHandler_get(CGAbstractExternMethod):
     # https://heycam.github.io/webidl/#LegacyPlatformObjectGetOwnProperty
     def getBody(self):
         getFromExpando = """\
-rooted!(in(cx) let mut expando = ptr::null_mut());
+rooted!(in(cx) let mut expando = ptr::null_mut::<JSObject>());
 get_expando_object(proxy, expando.handle_mut());
 if !expando.is_null() {
     let mut hasProp = false;
@@ -5406,7 +5406,7 @@ if args.callee() == new_target.get() {
 }
 
 // Step 6
-rooted!(in(cx) let mut prototype = ptr::null_mut());
+rooted!(in(cx) let mut prototype = ptr::null_mut::<JSObject>());
 {
     rooted!(in(cx) let mut proto_val = UndefinedValue());
     let _ac = JSAutoCompartment::new(cx, new_target.get());
@@ -6594,7 +6594,7 @@ class CGCallback(CGClass):
 
         bodyWithThis = string.Template(
             setupCall +
-            "rooted!(in(s.get_context()) let mut thisObjJS = ptr::null_mut());\n"
+            "rooted!(in(s.get_context()) let mut thisObjJS = ptr::null_mut::<JSObject>());\n"
             "wrap_call_this_object(s.get_context(), thisObj, thisObjJS.handle_mut());\n"
             "if thisObjJS.is_null() {\n"
             "    return Err(JSFailed);\n"
@@ -6605,7 +6605,7 @@ class CGCallback(CGClass):
             })
         bodyWithoutThis = string.Template(
             setupCall +
-            "rooted!(in(s.get_context()) let thisObjJS = ptr::null_mut());\n"
+            "rooted!(in(s.get_context()) let thisObjJS = ptr::null_mut::<JSObject>());\n"
             "return ${methodName}(${callArgs});").substitute({
                 "callArgs": ", ".join(argnamesWithoutThis),
                 "methodName": 'self.' + method.name,
diff --git a/components/script/dom/bindings/htmlconstructor.rs b/components/script/dom/bindings/htmlconstructor.rs
index c639dcca105..fb8640f0f91 100644
--- a/components/script/dom/bindings/htmlconstructor.rs
+++ b/components/script/dom/bindings/htmlconstructor.rs
@@ -81,7 +81,7 @@ use html5ever::LocalName;
 use html5ever::interface::QualName;
 use js::glue::UnwrapObject;
 use js::jsapi::{CallArgs, CurrentGlobalOrNull};
-use js::jsapi::{JSAutoCompartment, JSContext};
+use js::jsapi::{JSAutoCompartment, JSContext, JSObject};
 use js::jsapi::HandleObject;
 use js::jsapi::MutableHandleObject;
 use script_thread::ScriptThread;
@@ -111,7 +111,7 @@ pub unsafe fn html_constructor<T>(window: &Window, call_args: &CallArgs) -> Fall
 
     {
         let _ac = JSAutoCompartment::new(window.get_cx(), callee.get());
-        rooted!(in(window.get_cx()) let mut constructor = ptr::null_mut());
+        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() {
diff --git a/components/script/dom/bindings/interface.rs b/components/script/dom/bindings/interface.rs
index 7492cc9464e..5fc0c8a0590 100644
--- a/components/script/dom/bindings/interface.rs
+++ b/components/script/dom/bindings/interface.rs
@@ -186,7 +186,7 @@ pub unsafe fn create_interface_prototype_object(
     create_object(cx, proto, class, regular_methods, regular_properties, constants, rval);
 
     if !unscopable_names.is_empty() {
-        rooted!(in(cx) let mut unscopable_obj = ptr::null_mut());
+        rooted!(in(cx) let mut unscopable_obj = ptr::null_mut::<JSObject>());
         create_unscopable_object(cx, unscopable_names, unscopable_obj.handle_mut());
 
         let unscopable_symbol = GetWellKnownSymbol(cx, SymbolCode::unscopables);
@@ -231,7 +231,7 @@ pub unsafe fn create_named_constructors(
         global: HandleObject,
         named_constructors: &[(ConstructorClassHook, &[u8], u32)],
         interface_prototype_object: HandleObject) {
-    rooted!(in(cx) let mut constructor = ptr::null_mut());
+    rooted!(in(cx) let mut constructor = ptr::null_mut::<JSObject>());
 
     for &(native, name, arity) in named_constructors {
         assert!(*name.last().unwrap() == b'\0');
diff --git a/components/script/dom/bindings/iterable.rs b/components/script/dom/bindings/iterable.rs
index 183c17a2578..36cef24d4bd 100644
--- a/components/script/dom/bindings/iterable.rs
+++ b/components/script/dom/bindings/iterable.rs
@@ -16,7 +16,7 @@ use dom::bindings::trace::JSTraceable;
 use dom::globalscope::GlobalScope;
 use dom_struct::dom_struct;
 use js::conversions::ToJSValConvertible;
-use js::jsapi::{HandleValue, Heap, JSContext, MutableHandleObject};
+use js::jsapi::{HandleValue, Heap, JSContext, MutableHandleObject, JSObject};
 use js::jsval::UndefinedValue;
 use std::cell::Cell;
 use std::ptr;
@@ -76,7 +76,7 @@ impl<T: DomObject + JSTraceable + Iterable> IterableIterator<T> {
     pub fn Next(&self, cx: *mut JSContext) -> Fallible<NonNullJSObjectPtr> {
         let index = self.index.get();
         rooted!(in(cx) let mut value = UndefinedValue());
-        rooted!(in(cx) let mut rval = ptr::null_mut());
+        rooted!(in(cx) let mut rval = ptr::null_mut::<JSObject>());
         let result = if index >= self.iterable.get_iterable_length() {
             dict_return(cx, rval.handle_mut(), true, value.handle())
         } else {
diff --git a/components/script/dom/bindings/proxyhandler.rs b/components/script/dom/bindings/proxyhandler.rs
index a604a34e377..4774425d531 100644
--- a/components/script/dom/bindings/proxyhandler.rs
+++ b/components/script/dom/bindings/proxyhandler.rs
@@ -32,7 +32,7 @@ pub unsafe extern "C" fn shadow_check_callback(cx: *mut JSContext,
                                                -> DOMProxyShadowsResult {
     // TODO: support OverrideBuiltins when #12978 is fixed.
 
-    rooted!(in(cx) let mut expando = ptr::null_mut());
+    rooted!(in(cx) let mut expando = ptr::null_mut::<JSObject>());
     get_expando_object(object, expando.handle_mut());
     if !expando.get().is_null() {
         let mut has_own = false;
@@ -73,7 +73,7 @@ pub unsafe extern "C" fn get_property_descriptor(cx: *mut JSContext,
         return true;
     }
 
-    rooted!(in(cx) let mut proto = ptr::null_mut());
+    rooted!(in(cx) let mut proto = ptr::null_mut::<JSObject>());
     if !GetObjectProto(cx, proxy, proto.handle_mut()) {
         // FIXME(#11868) Should assign to desc.obj, desc.get() is a copy.
         desc.get().obj = ptr::null_mut();
@@ -95,7 +95,7 @@ pub unsafe extern "C" fn define_property(cx: *mut JSContext,
         return true;
     }
 
-    rooted!(in(cx) let mut expando = ptr::null_mut());
+    rooted!(in(cx) let mut expando = ptr::null_mut::<JSObject>());
     ensure_expando_object(cx, proxy, expando.handle_mut());
     JS_DefinePropertyById(cx, expando.handle(), id, desc, result)
 }
@@ -106,7 +106,7 @@ pub unsafe extern "C" fn delete(cx: *mut JSContext,
                                 id: HandleId,
                                 bp: *mut ObjectOpResult)
                                 -> bool {
-    rooted!(in(cx) let mut expando = ptr::null_mut());
+    rooted!(in(cx) let mut expando = ptr::null_mut::<JSObject>());
     get_expando_object(proxy, expando.handle_mut());
     if expando.is_null() {
         (*bp).code_ = 0 /* OkCode */;
diff --git a/components/script/dom/bindings/utils.rs b/components/script/dom/bindings/utils.rs
index 2a23281c8fe..4a6d19f972a 100644
--- a/components/script/dom/bindings/utils.rs
+++ b/components/script/dom/bindings/utils.rs
@@ -134,7 +134,7 @@ pub unsafe fn get_property_on_prototype(cx: *mut JSContext,
                                         found: *mut bool,
                                         vp: MutableHandleValue)
                                         -> bool {
-    rooted!(in(cx) let mut proto = ptr::null_mut());
+    rooted!(in(cx) let mut proto = ptr::null_mut::<JSObject>());
     if !JS_GetPrototype(cx, proxy, proto.handle_mut()) || proto.is_null() {
         *found = false;
         return true;
@@ -287,7 +287,7 @@ pub unsafe fn has_property_on_prototype(cx: *mut JSContext,
                                         id: HandleId,
                                         found: &mut bool)
                                         -> bool {
-    rooted!(in(cx) let mut proto = ptr::null_mut());
+    rooted!(in(cx) let mut proto = ptr::null_mut::<JSObject>());
     if !JS_GetPrototype(cx, proxy, proto.handle_mut()) {
         return false;
     }
diff --git a/components/script/dom/customelementregistry.rs b/components/script/dom/customelementregistry.rs
index 21276d8f5bb..99b38717ac2 100644
--- a/components/script/dom/customelementregistry.rs
+++ b/components/script/dom/customelementregistry.rs
@@ -29,7 +29,7 @@ use html5ever::{LocalName, Namespace, Prefix};
 use js::conversions::ToJSValConvertible;
 use js::glue::UnwrapObject;
 use js::jsapi::{Construct1, IsCallable, IsConstructor, HandleValueArray, HandleObject, MutableHandleValue};
-use js::jsapi::{Heap, JS_GetProperty, JS_SameValue, JSAutoCompartment, JSContext};
+use js::jsapi::{Heap, JS_GetProperty, JS_SameValue, JSAutoCompartment, JSContext, JSObject};
 use js::jsval::{JSVal, NullValue, ObjectValue, UndefinedValue};
 use microtask::Microtask;
 use script_thread::ScriptThread;
@@ -436,7 +436,7 @@ impl CustomElementDefinition {
         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());
+        rooted!(in(cx) let mut element = ptr::null_mut::<JSObject>());
         {
             // Go into the constructor's compartment
             let _ac = JSAutoCompartment::new(cx, self.constructor.callback());
@@ -545,7 +545,7 @@ fn run_upgrade_constructor(constructor: &Rc<Function>, element: &Element) -> Err
     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()); }
-    rooted!(in(cx) let mut construct_result = ptr::null_mut());
+    rooted!(in(cx) let mut construct_result = ptr::null_mut::<JSObject>());
     {
         // Go into the constructor's compartment
         let _ac = JSAutoCompartment::new(cx, constructor.callback());
diff --git a/components/script/dom/eventtarget.rs b/components/script/dom/eventtarget.rs
index 43a0a3502a3..426752e42d5 100644
--- a/components/script/dom/eventtarget.rs
+++ b/components/script/dom/eventtarget.rs
@@ -34,7 +34,7 @@ use dom::virtualmethods::VirtualMethods;
 use dom::window::Window;
 use dom_struct::dom_struct;
 use fnv::FnvHasher;
-use js::jsapi::{CompileFunction, JS_GetFunctionObject, JSAutoCompartment};
+use js::jsapi::{CompileFunction, JS_GetFunctionObject, JSAutoCompartment, JSFunction};
 use js::rust::{AutoObjectVectorWrapper, CompileOptionsWrapper};
 use libc::{c_char, size_t};
 use servo_atoms::Atom;
@@ -443,7 +443,7 @@ impl EventTarget {
         let scopechain = AutoObjectVectorWrapper::new(cx);
 
         let _ac = JSAutoCompartment::new(cx, window.reflector().get_jsobject().get());
-        rooted!(in(cx) let mut handler = ptr::null_mut());
+        rooted!(in(cx) let mut handler = ptr::null_mut::<JSFunction>());
         let rv = unsafe {
             CompileFunction(cx,
                             scopechain.ptr,
diff --git a/components/script/dom/filereader.rs b/components/script/dom/filereader.rs
index 7a2674f293a..7475e4adbd6 100644
--- a/components/script/dom/filereader.rs
+++ b/components/script/dom/filereader.rs
@@ -26,6 +26,7 @@ use hyper::mime::{Attr, Mime};
 use js::jsapi::Heap;
 use js::jsapi::JSAutoCompartment;
 use js::jsapi::JSContext;
+use js::jsapi::JSObject;
 use js::jsval::{self, JSVal};
 use js::typedarray::{ArrayBuffer, CreateWith};
 use servo_atoms::Atom;
@@ -261,7 +262,7 @@ impl FileReader {
     fn perform_readasarraybuffer(result: &DomRefCell<Option<FileReaderResult>>,
         cx: *mut JSContext, _: ReadMetaData, bytes: &[u8]) {
         unsafe {
-            rooted!(in(cx) let mut array_buffer = ptr::null_mut());
+            rooted!(in(cx) let mut array_buffer = ptr::null_mut::<JSObject>());
             assert!(ArrayBuffer::create(cx, CreateWith::Slice(bytes), array_buffer.handle_mut()).is_ok());
 
             *result.borrow_mut() = Some(FileReaderResult::ArrayBuffer(Heap::default()));
diff --git a/components/script/dom/gamepad.rs b/components/script/dom/gamepad.rs
index 99f52cb203f..e5381d5587b 100644
--- a/components/script/dom/gamepad.rs
+++ b/components/script/dom/gamepad.rs
@@ -93,7 +93,7 @@ impl Gamepad {
         );
 
         let cx = global.get_cx();
-        rooted!(in (cx) let mut array = ptr::null_mut());
+        rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
         unsafe {
             let _ = Float64Array::create(cx, CreateWith::Slice(&state.axes), array.handle_mut());
         }
diff --git a/components/script/dom/imagedata.rs b/components/script/dom/imagedata.rs
index f0270fbe7b7..6be4e5d89c2 100644
--- a/components/script/dom/imagedata.rs
+++ b/components/script/dom/imagedata.rs
@@ -36,7 +36,7 @@ impl ImageData {
         let len = width * height * 4;
         unsafe {
             let cx = global.get_cx();
-            rooted!(in (cx) let mut js_object = ptr::null_mut());
+            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);
@@ -103,7 +103,7 @@ impl ImageData {
         } else {
             let len = width * height * 4;
             let cx = global.get_cx();
-            rooted!(in (cx) let mut array = ptr::null_mut());
+            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 7e2e5f3f825..eda9021e64c 100644
--- a/components/script/dom/paintworkletglobalscope.rs
+++ b/components/script/dom/paintworkletglobalscope.rs
@@ -35,6 +35,7 @@ use js::jsapi::Heap;
 use js::jsapi::IsCallable;
 use js::jsapi::IsConstructor;
 use js::jsapi::JSAutoCompartment;
+use js::jsapi::JSObject;
 use js::jsapi::JS_ClearPendingException;
 use js::jsapi::JS_IsExceptionPending;
 use js::jsapi::JS_NewArrayObject;
@@ -240,7 +241,7 @@ impl PaintWorkletGlobalScope {
             Entry::Vacant(entry) => {
                 // Step 5.2-5.3
                 let args = HandleValueArray::new();
-                rooted!(in(cx) let mut result = null_mut());
+                rooted!(in(cx) let mut result = null_mut::<JSObject>());
                 unsafe { Construct1(cx, class_constructor.handle(), &args, result.handle_mut()); }
                 paint_instance.set(ObjectValue(result.get()));
                 if unsafe { JS_IsExceptionPending(cx) } {
diff --git a/components/script/dom/promise.rs b/components/script/dom/promise.rs
index df9838ed5cc..20485618c18 100644
--- a/components/script/dom/promise.rs
+++ b/components/script/dom/promise.rs
@@ -72,7 +72,7 @@ impl Promise {
     #[allow(unsafe_code)]
     pub fn new(global: &GlobalScope) -> Rc<Promise> {
         let cx = global.get_cx();
-        rooted!(in(cx) let mut obj = ptr::null_mut());
+        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)
diff --git a/components/script/dom/textencoder.rs b/components/script/dom/textencoder.rs
index 7ca2a429525..8fb97ac9e78 100644
--- a/components/script/dom/textencoder.rs
+++ b/components/script/dom/textencoder.rs
@@ -11,7 +11,7 @@ use dom::bindings::root::DomRoot;
 use dom::bindings::str::{DOMString, USVString};
 use dom::globalscope::GlobalScope;
 use dom_struct::dom_struct;
-use js::jsapi::JSContext;
+use js::jsapi::{JSContext, JSObject};
 use js::typedarray::{Uint8Array, CreateWith};
 use std::ptr;
 
@@ -50,7 +50,7 @@ impl TextEncoderMethods for TextEncoder {
     unsafe fn Encode(&self, cx: *mut JSContext, input: USVString) -> NonNullJSObjectPtr {
         let encoded = input.0.as_bytes();
 
-        rooted!(in(cx) let mut js_object = ptr::null_mut());
+        rooted!(in(cx) let mut js_object = ptr::null_mut::<JSObject>());
         assert!(Uint8Array::create(cx, CreateWith::Slice(&encoded), js_object.handle_mut()).is_ok());
 
         NonNullJSObjectPtr::new_unchecked(js_object.get())
diff --git a/components/script/dom/vreyeparameters.rs b/components/script/dom/vreyeparameters.rs
index b573d3d96b8..496277ba65d 100644
--- a/components/script/dom/vreyeparameters.rs
+++ b/components/script/dom/vreyeparameters.rs
@@ -43,7 +43,7 @@ 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());
+        rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
         unsafe {
             let _ = Float32Array::create(cx, CreateWith::Slice(&parameters.offset), array.handle_mut());
         }
diff --git a/components/script/dom/vrframedata.rs b/components/script/dom/vrframedata.rs
index 0c36536e4b7..530a3727020 100644
--- a/components/script/dom/vrframedata.rs
+++ b/components/script/dom/vrframedata.rs
@@ -73,7 +73,7 @@ impl VRFrameData {
 
 #[allow(unsafe_code)]
 fn create_typed_array(cx: *mut JSContext, src: &[f32], dst: &Heap<*mut JSObject>) {
-    rooted!(in (cx) let mut array = ptr::null_mut());
+    rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
     unsafe {
         let _ = Float32Array::create(cx, CreateWith::Slice(src), array.handle_mut());
     }
diff --git a/components/script/dom/vrpose.rs b/components/script/dom/vrpose.rs
index b6a9fad10a0..a0b3ec7c92a 100644
--- a/components/script/dom/vrpose.rs
+++ b/components/script/dom/vrpose.rs
@@ -32,7 +32,7 @@ unsafe fn update_or_create_typed_array(cx: *mut JSContext,
     match src {
         Some(data) => {
             if dst.get().is_null() {
-                rooted!(in (cx) let mut array = ptr::null_mut());
+                rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
                 let _ = Float32Array::create(cx, CreateWith::Slice(data), array.handle_mut());
                 (*dst).set(array.get());
             } else {
diff --git a/components/script/dom/vrstageparameters.rs b/components/script/dom/vrstageparameters.rs
index fa545621001..9a34af4c03e 100644
--- a/components/script/dom/vrstageparameters.rs
+++ b/components/script/dom/vrstageparameters.rs
@@ -38,7 +38,7 @@ impl VRStageParameters {
     #[allow(unsafe_code)]
     pub fn new(parameters: WebVRStageParameters, global: &GlobalScope) -> DomRoot<VRStageParameters> {
         let cx = global.get_cx();
-        rooted!(in (cx) let mut array = ptr::null_mut());
+        rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
         unsafe {
             let _ = Float32Array::create(cx, CreateWith::Slice(&parameters.sitting_to_standing_transform),
                                                                array.handle_mut());
diff --git a/components/script/dom/websocket.rs b/components/script/dom/websocket.rs
index 5fc38aa0ac8..df67630119b 100644
--- a/components/script/dom/websocket.rs
+++ b/components/script/dom/websocket.rs
@@ -22,7 +22,7 @@ use dom::globalscope::GlobalScope;
 use dom::messageevent::MessageEvent;
 use dom_struct::dom_struct;
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
-use js::jsapi::JSAutoCompartment;
+use js::jsapi::{JSAutoCompartment, JSObject};
 use js::jsval::UndefinedValue;
 use js::typedarray::{ArrayBuffer, CreateWith};
 use net_traits::{CoreResourceMsg, FetchChannels};
@@ -510,7 +510,7 @@ impl TaskOnce for MessageReceivedTask {
                             blob.to_jsval(cx, message.handle_mut());
                         }
                         BinaryType::Arraybuffer => {
-                            rooted!(in(cx) let mut array_buffer = ptr::null_mut());
+                            rooted!(in(cx) let mut array_buffer = ptr::null_mut::<JSObject>());
                             assert!(ArrayBuffer::create(cx,
                                                         CreateWith::Slice(&data),
                                                         array_buffer.handle_mut())
diff --git a/components/script/dom/xmlhttprequest.rs b/components/script/dom/xmlhttprequest.rs
index a316ed8b898..716115307d2 100644
--- a/components/script/dom/xmlhttprequest.rs
+++ b/components/script/dom/xmlhttprequest.rs
@@ -1129,7 +1129,7 @@ impl XMLHttpRequest {
 
         // Step 2
         let bytes = self.response.borrow();
-        rooted!(in(cx) let mut array_buffer = ptr::null_mut());
+        rooted!(in(cx) let mut array_buffer = ptr::null_mut::<JSObject>());
         ArrayBuffer::create(cx, CreateWith::Slice(&bytes), array_buffer.handle_mut()).ok().and_then(|()| {
             self.response_arraybuffer.set(array_buffer.get());
             Some(NonNullJSObjectPtr::new_unchecked(array_buffer.get()))