Merge remote-tracking branch 'upstream/master' into feat-cow-infra

`tests/wpt/web-platform-tests/html/browsers/origin/cross-origin-objects/cross-origin-objects.html`
was reverted to the upstream version.

1 files changed, 460 insertions, 0 deletions

diff --git a/components/script/dom/bindings/htmlconstructor.rs b/components/script/dom/bindings/htmlconstructor.rs
new file mode 100644
index 00000000000..76d717ff4b7
--- /dev/null
+++ b/components/script/dom/bindings/htmlconstructor.rs
@@ -0,0 +1,460 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use crate::dom::bindings::codegen::Bindings::HTMLAnchorElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLAreaElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLAudioElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLBRElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLBaseElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLBodyElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLButtonElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLCanvasElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLDListElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLDataElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLDataListElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLDetailsElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLDialogElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLDirectoryElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLDivElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLEmbedElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLFieldSetElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLFontElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLFormElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLFrameElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLFrameSetElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLHRElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLHeadElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLHeadingElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLHtmlElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLIFrameElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLImageElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLInputElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLLIElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLLabelElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLLegendElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLLinkElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLMapElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLMenuElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLMetaElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLMeterElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLModElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLOListElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLObjectElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLOptGroupElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLOptionElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLOutputElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLParagraphElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLParamElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLPictureElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLPreElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLProgressElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLQuoteElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLScriptElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLSelectElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLSourceElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLSpanElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLStyleElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTableCaptionElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTableCellElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTableColElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTableElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTableRowElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTableSectionElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTemplateElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTextAreaElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTimeElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTitleElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLTrackElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLUListElementBinding;
+use crate::dom::bindings::codegen::Bindings::HTMLVideoElementBinding;
+use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
+use crate::dom::bindings::conversions::DerivedFrom;
+use crate::dom::bindings::error::{throw_dom_exception, Error};
+use crate::dom::bindings::inheritance::Castable;
+use crate::dom::bindings::reflector::DomObject;
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::create::create_native_html_element;
+use crate::dom::customelementregistry::{ConstructionStackEntry, CustomElementState};
+use crate::dom::element::{Element, ElementCreator};
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::htmlelement::HTMLElement;
+use crate::dom::window::Window;
+use crate::script_runtime::JSContext;
+use crate::script_thread::ScriptThread;
+use html5ever::interface::QualName;
+use html5ever::LocalName;
+use js::conversions::ToJSValConvertible;
+use js::glue::{UnwrapObjectDynamic, UnwrapObjectStatic};
+use js::jsapi::{CallArgs, CurrentGlobalOrNull};
+use js::jsapi::{JSAutoRealm, JSObject};
+use js::jsval::UndefinedValue;
+use js::rust::wrappers::{JS_GetProperty, JS_SetPrototype, JS_WrapObject};
+use js::rust::{HandleObject, MutableHandleObject, MutableHandleValue};
+use std::ptr;
+
+// https://html.spec.whatwg.org/multipage/#htmlconstructor
+unsafe fn html_constructor(
+    cx: JSContext,
+    window: &Window,
+    call_args: &CallArgs,
+    check_type: fn(&Element) -> bool,
+    get_proto_object: fn(JSContext, HandleObject, MutableHandleObject),
+) -> Result<(), ()> {
+    let document = window.Document();
+    let global = window.upcast::<GlobalScope>();
+
+    // Step 1
+    let registry = window.CustomElements();
+
+    // Step 2 https://html.spec.whatwg.org/multipage/#htmlconstructor
+    // The custom element definition cannot use an element interface as its constructor
+
+    // The new_target might be a cross-compartment wrapper. Get the underlying object
+    // so we can do the spec's object-identity checks.
+    rooted!(in(*cx) let new_target_unwrapped = UnwrapObjectDynamic(call_args.new_target().to_object(), *cx, 1));
+    if new_target_unwrapped.is_null() {
+        throw_dom_exception(cx, global, Error::Type("new.target is null".to_owned()));
+        return Err(());
+    }
+    if call_args.callee() == new_target_unwrapped.get() {
+        throw_dom_exception(
+            cx,
+            global,
+            Error::Type("new.target must not be the active function object".to_owned()),
+        );
+        return Err(());
+    }
+
+    // Step 3
+    rooted!(in(*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 => {
+            throw_dom_exception(
+                cx,
+                global,
+                Error::Type("No custom element definition found for new.target".to_owned()),
+            );
+            return Err(());
+        },
+    };
+
+    rooted!(in(*cx) let callee = UnwrapObjectStatic(call_args.callee()));
+    if callee.is_null() {
+        throw_dom_exception(cx, global, Error::Security);
+        return Err(());
+    }
+
+    {
+        let _ac = JSAutoRealm::new(*cx, callee.get());
+        rooted!(in(*cx) let mut constructor = ptr::null_mut::<JSObject>());
+        rooted!(in(*cx) let global_object = CurrentGlobalOrNull(*cx));
+
+        if definition.is_autonomous() {
+            // Step 4
+            // Since this element is autonomous, its active function object must be the HTMLElement
+
+            // Retrieve the constructor object for HTMLElement
+            HTMLElementBinding::GetConstructorObject(
+                cx,
+                global_object.handle(),
+                constructor.handle_mut(),
+            );
+        } else {
+            // Step 5
+            get_constructor_object_from_local_name(
+                definition.local_name.clone(),
+                cx,
+                global_object.handle(),
+                constructor.handle_mut(),
+            );
+        }
+        // Callee must be the same as the element interface's constructor object.
+        if constructor.get() != callee.get() {
+            throw_dom_exception(
+                cx,
+                global,
+                Error::Type("Custom element does not extend the proper interface".to_owned()),
+            );
+            return Err(());
+        }
+    }
+
+    // Step 6
+    rooted!(in(*cx) let mut prototype = ptr::null_mut::<JSObject>());
+    {
+        rooted!(in(*cx) let mut proto_val = UndefinedValue());
+        let _ac = JSAutoRealm::new(*cx, new_target_unwrapped.get());
+        if !JS_GetProperty(
+            *cx,
+            new_target_unwrapped.handle(),
+            b"prototype\0".as_ptr() as *const _,
+            proto_val.handle_mut(),
+        ) {
+            return Err(());
+        }
+
+        if !proto_val.is_object() {
+            // Step 7 of https://html.spec.whatwg.org/multipage/#htmlconstructor.
+            // This fallback behavior is designed to match analogous behavior for the
+            // JavaScript built-ins. So we enter the realm of our underlying
+            // newTarget object and fall back to the prototype object from that global.
+            // XXX The spec says to use GetFunctionRealm(), which is not actually
+            // the same thing as what we have here (e.g. in the case of scripted callable proxies
+            // whose target is not same-realm with the proxy, or bound functions, etc).
+            // https://bugzilla.mozilla.org/show_bug.cgi?id=1317658
+
+            rooted!(in(*cx) let global_object = CurrentGlobalOrNull(*cx));
+            get_proto_object(cx, global_object.handle(), prototype.handle_mut());
+        } else {
+            // Step 6
+            prototype.set(proto_val.to_object());
+        }
+    }
+
+    // Wrap prototype in this context since it is from the newTarget realm
+    if !JS_WrapObject(*cx, prototype.handle_mut()) {
+        return Err(());
+    }
+
+    let entry = definition.construction_stack.borrow().last().cloned();
+    let result = match entry {
+        // Step 8
+        None => {
+            // Step 8.1
+            let name = QualName::new(None, ns!(html), definition.local_name.clone());
+            let element = if definition.is_autonomous() {
+                DomRoot::upcast(HTMLElement::new(name.local, None, &*document))
+            } else {
+                create_native_html_element(name, None, &*document, ElementCreator::ScriptCreated)
+            };
+
+            // Step 8.2 is performed in the generated caller code.
+
+            // Step 8.3
+            element.set_custom_element_state(CustomElementState::Custom);
+
+            // Step 8.4
+            element.set_custom_element_definition(definition.clone());
+
+            // Step 8.5
+            if !check_type(&*element) {
+                throw_dom_exception(cx, global, Error::InvalidState);
+                return Err(());
+            } else {
+                element
+            }
+        },
+        // Step 9
+        Some(ConstructionStackEntry::Element(element)) => {
+            // Step 11 is performed in the generated caller code.
+
+            // Step 12
+            let mut construction_stack = definition.construction_stack.borrow_mut();
+            construction_stack.pop();
+            construction_stack.push(ConstructionStackEntry::AlreadyConstructedMarker);
+
+            // Step 13
+            if !check_type(&*element) {
+                throw_dom_exception(cx, global, Error::InvalidState);
+                return Err(());
+            } else {
+                element
+            }
+        },
+        // Step 10
+        Some(ConstructionStackEntry::AlreadyConstructedMarker) => {
+            let s = "Top of construction stack marked AlreadyConstructed due to \
+                     a custom element constructor constructing itself after super()"
+                .to_string();
+            throw_dom_exception(cx, global, Error::Type(s));
+            return Err(());
+        },
+    };
+
+    rooted!(in(*cx) let mut element = result.reflector().get_jsobject().get());
+    if !JS_WrapObject(*cx, element.handle_mut()) {
+        return Err(());
+    }
+
+    JS_SetPrototype(*cx, element.handle(), prototype.handle());
+
+    result.to_jsval(*cx, MutableHandleValue::from_raw(call_args.rval()));
+    Ok(())
+}
+
+/// Returns the constructor object for the element associated with the given local name.
+/// This list should only include elements marked with the [HTMLConstructor] extended attribute.
+pub fn get_constructor_object_from_local_name(
+    name: LocalName,
+    cx: JSContext,
+    global: HandleObject,
+    rval: MutableHandleObject,
+) -> bool {
+    macro_rules! get_constructor(
+        ($binding:ident) => ({
+            $binding::GetConstructorObject(cx, global, rval);
+            true
+        })
+    );
+
+    match name {
+        local_name!("a") => get_constructor!(HTMLAnchorElementBinding),
+        local_name!("abbr") => get_constructor!(HTMLElementBinding),
+        local_name!("acronym") => get_constructor!(HTMLElementBinding),
+        local_name!("address") => get_constructor!(HTMLElementBinding),
+        local_name!("area") => get_constructor!(HTMLAreaElementBinding),
+        local_name!("article") => get_constructor!(HTMLElementBinding),
+        local_name!("aside") => get_constructor!(HTMLElementBinding),
+        local_name!("audio") => get_constructor!(HTMLAudioElementBinding),
+        local_name!("b") => get_constructor!(HTMLElementBinding),
+        local_name!("base") => get_constructor!(HTMLBaseElementBinding),
+        local_name!("bdi") => get_constructor!(HTMLElementBinding),
+        local_name!("bdo") => get_constructor!(HTMLElementBinding),
+        local_name!("big") => get_constructor!(HTMLElementBinding),
+        local_name!("blockquote") => get_constructor!(HTMLQuoteElementBinding),
+        local_name!("body") => get_constructor!(HTMLBodyElementBinding),
+        local_name!("br") => get_constructor!(HTMLBRElementBinding),
+        local_name!("button") => get_constructor!(HTMLButtonElementBinding),
+        local_name!("canvas") => get_constructor!(HTMLCanvasElementBinding),
+        local_name!("caption") => get_constructor!(HTMLTableCaptionElementBinding),
+        local_name!("center") => get_constructor!(HTMLElementBinding),
+        local_name!("cite") => get_constructor!(HTMLElementBinding),
+        local_name!("code") => get_constructor!(HTMLElementBinding),
+        local_name!("col") => get_constructor!(HTMLTableColElementBinding),
+        local_name!("colgroup") => get_constructor!(HTMLTableColElementBinding),
+        local_name!("data") => get_constructor!(HTMLDataElementBinding),
+        local_name!("datalist") => get_constructor!(HTMLDataListElementBinding),
+        local_name!("dd") => get_constructor!(HTMLElementBinding),
+        local_name!("del") => get_constructor!(HTMLModElementBinding),
+        local_name!("details") => get_constructor!(HTMLDetailsElementBinding),
+        local_name!("dfn") => get_constructor!(HTMLElementBinding),
+        local_name!("dialog") => get_constructor!(HTMLDialogElementBinding),
+        local_name!("dir") => get_constructor!(HTMLDirectoryElementBinding),
+        local_name!("div") => get_constructor!(HTMLDivElementBinding),
+        local_name!("dl") => get_constructor!(HTMLDListElementBinding),
+        local_name!("dt") => get_constructor!(HTMLElementBinding),
+        local_name!("em") => get_constructor!(HTMLElementBinding),
+        local_name!("embed") => get_constructor!(HTMLEmbedElementBinding),
+        local_name!("fieldset") => get_constructor!(HTMLFieldSetElementBinding),
+        local_name!("figcaption") => get_constructor!(HTMLElementBinding),
+        local_name!("figure") => get_constructor!(HTMLElementBinding),
+        local_name!("font") => get_constructor!(HTMLFontElementBinding),
+        local_name!("footer") => get_constructor!(HTMLElementBinding),
+        local_name!("form") => get_constructor!(HTMLFormElementBinding),
+        local_name!("frame") => get_constructor!(HTMLFrameElementBinding),
+        local_name!("frameset") => get_constructor!(HTMLFrameSetElementBinding),
+        local_name!("h1") => get_constructor!(HTMLHeadingElementBinding),
+        local_name!("h2") => get_constructor!(HTMLHeadingElementBinding),
+        local_name!("h3") => get_constructor!(HTMLHeadingElementBinding),
+        local_name!("h4") => get_constructor!(HTMLHeadingElementBinding),
+        local_name!("h5") => get_constructor!(HTMLHeadingElementBinding),
+        local_name!("h6") => get_constructor!(HTMLHeadingElementBinding),
+        local_name!("head") => get_constructor!(HTMLHeadElementBinding),
+        local_name!("header") => get_constructor!(HTMLElementBinding),
+        local_name!("hgroup") => get_constructor!(HTMLElementBinding),
+        local_name!("hr") => get_constructor!(HTMLHRElementBinding),
+        local_name!("html") => get_constructor!(HTMLHtmlElementBinding),
+        local_name!("i") => get_constructor!(HTMLElementBinding),
+        local_name!("iframe") => get_constructor!(HTMLIFrameElementBinding),
+        local_name!("img") => get_constructor!(HTMLImageElementBinding),
+        local_name!("input") => get_constructor!(HTMLInputElementBinding),
+        local_name!("ins") => get_constructor!(HTMLModElementBinding),
+        local_name!("kbd") => get_constructor!(HTMLElementBinding),
+        local_name!("label") => get_constructor!(HTMLLabelElementBinding),
+        local_name!("legend") => get_constructor!(HTMLLegendElementBinding),
+        local_name!("li") => get_constructor!(HTMLLIElementBinding),
+        local_name!("link") => get_constructor!(HTMLLinkElementBinding),
+        local_name!("listing") => get_constructor!(HTMLPreElementBinding),
+        local_name!("main") => get_constructor!(HTMLElementBinding),
+        local_name!("map") => get_constructor!(HTMLMapElementBinding),
+        local_name!("mark") => get_constructor!(HTMLElementBinding),
+        local_name!("marquee") => get_constructor!(HTMLElementBinding),
+        local_name!("menu") => get_constructor!(HTMLMenuElementBinding),
+        local_name!("meta") => get_constructor!(HTMLMetaElementBinding),
+        local_name!("meter") => get_constructor!(HTMLMeterElementBinding),
+        local_name!("nav") => get_constructor!(HTMLElementBinding),
+        local_name!("nobr") => get_constructor!(HTMLElementBinding),
+        local_name!("noframes") => get_constructor!(HTMLElementBinding),
+        local_name!("noscript") => get_constructor!(HTMLElementBinding),
+        local_name!("object") => get_constructor!(HTMLObjectElementBinding),
+        local_name!("ol") => get_constructor!(HTMLOListElementBinding),
+        local_name!("optgroup") => get_constructor!(HTMLOptGroupElementBinding),
+        local_name!("option") => get_constructor!(HTMLOptionElementBinding),
+        local_name!("output") => get_constructor!(HTMLOutputElementBinding),
+        local_name!("p") => get_constructor!(HTMLParagraphElementBinding),
+        local_name!("param") => get_constructor!(HTMLParamElementBinding),
+        local_name!("picture") => get_constructor!(HTMLPictureElementBinding),
+        local_name!("plaintext") => get_constructor!(HTMLPreElementBinding),
+        local_name!("pre") => get_constructor!(HTMLPreElementBinding),
+        local_name!("progress") => get_constructor!(HTMLProgressElementBinding),
+        local_name!("q") => get_constructor!(HTMLQuoteElementBinding),
+        local_name!("rp") => get_constructor!(HTMLElementBinding),
+        local_name!("rt") => get_constructor!(HTMLElementBinding),
+        local_name!("ruby") => get_constructor!(HTMLElementBinding),
+        local_name!("s") => get_constructor!(HTMLElementBinding),
+        local_name!("samp") => get_constructor!(HTMLElementBinding),
+        local_name!("script") => get_constructor!(HTMLScriptElementBinding),
+        local_name!("section") => get_constructor!(HTMLElementBinding),
+        local_name!("select") => get_constructor!(HTMLSelectElementBinding),
+        local_name!("small") => get_constructor!(HTMLElementBinding),
+        local_name!("source") => get_constructor!(HTMLSourceElementBinding),
+        local_name!("span") => get_constructor!(HTMLSpanElementBinding),
+        local_name!("strike") => get_constructor!(HTMLElementBinding),
+        local_name!("strong") => get_constructor!(HTMLElementBinding),
+        local_name!("style") => get_constructor!(HTMLStyleElementBinding),
+        local_name!("sub") => get_constructor!(HTMLElementBinding),
+        local_name!("summary") => get_constructor!(HTMLElementBinding),
+        local_name!("sup") => get_constructor!(HTMLElementBinding),
+        local_name!("table") => get_constructor!(HTMLTableElementBinding),
+        local_name!("tbody") => get_constructor!(HTMLTableSectionElementBinding),
+        local_name!("td") => get_constructor!(HTMLTableCellElementBinding),
+        local_name!("template") => get_constructor!(HTMLTemplateElementBinding),
+        local_name!("textarea") => get_constructor!(HTMLTextAreaElementBinding),
+        local_name!("tfoot") => get_constructor!(HTMLTableSectionElementBinding),
+        local_name!("th") => get_constructor!(HTMLTableCellElementBinding),
+        local_name!("thead") => get_constructor!(HTMLTableSectionElementBinding),
+        local_name!("time") => get_constructor!(HTMLTimeElementBinding),
+        local_name!("title") => get_constructor!(HTMLTitleElementBinding),
+        local_name!("tr") => get_constructor!(HTMLTableRowElementBinding),
+        local_name!("tt") => get_constructor!(HTMLElementBinding),
+        local_name!("track") => get_constructor!(HTMLTrackElementBinding),
+        local_name!("u") => get_constructor!(HTMLElementBinding),
+        local_name!("ul") => get_constructor!(HTMLUListElementBinding),
+        local_name!("var") => get_constructor!(HTMLElementBinding),
+        local_name!("video") => get_constructor!(HTMLVideoElementBinding),
+        local_name!("wbr") => get_constructor!(HTMLElementBinding),
+        local_name!("xmp") => get_constructor!(HTMLPreElementBinding),
+        _ => false,
+    }
+}
+
+pub fn pop_current_element_queue() {
+    ScriptThread::pop_current_element_queue();
+}
+
+pub fn push_new_element_queue() {
+    ScriptThread::push_new_element_queue();
+}
+
+pub(crate) unsafe fn call_html_constructor<T: DerivedFrom<Element> + DomObject>(
+    cx: JSContext,
+    args: &CallArgs,
+    global: &Window,
+    get_proto_object: fn(JSContext, HandleObject, MutableHandleObject),
+) -> bool {
+    fn element_derives_interface<T: DerivedFrom<Element>>(element: &Element) -> bool {
+        element.is::<T>()
+    }
+
+    html_constructor(
+        cx,
+        global,
+        args,
+        element_derives_interface::<T>,
+        get_proto_object,
+    )
+    .is_ok()
+}