Introduce DynamicModuleOwner dom struct

components/script/dom/bindings/codegen/Bindings.conf

@@ -47,6 +47,10 @@ DOMInterfaces = {
     'inRealms': ['PromiseAttribute', 'PromiseNativeHandler'],
 },
 
+'DynamicModuleOwner': {
+    'inRealms': ['PromiseAttribute'],
+},
+
 'URL': {
     'weakReferenceable': True,
 },

components/script/dom/dynamicmoduleowner.rs

@@ -0,0 +1,54 @@
+/* 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::DynamicModuleOwnerBinding::DynamicModuleOwnerMethods;
+use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::promise::Promise;
+use dom_struct::dom_struct;
+use std::rc::Rc;
+use uuid::Uuid;
+
+/// An unique id for dynamic module
+#[derive(Clone, Copy, Debug, Eq, Hash, JSTraceable, PartialEq)]
+pub struct DynamicModuleId(pub Uuid);
+
+#[dom_struct]
+pub struct DynamicModuleOwner {
+    reflector_: Reflector,
+
+    #[ignore_malloc_size_of = "Rc"]
+    promise: Rc<Promise>,
+
+    /// Unique id for each dynamic module
+    #[ignore_malloc_size_of = "Defined in uuid"]
+    id: DynamicModuleId,
+}
+
+impl DynamicModuleOwner {
+    #[allow(unrooted_must_root)]
+    fn new_inherited(promise: Rc<Promise>, id: DynamicModuleId) -> Self {
+        DynamicModuleOwner {
+            reflector_: Reflector::new(),
+            promise,
+            id,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(global: &GlobalScope, promise: Rc<Promise>, id: DynamicModuleId) -> DomRoot<Self> {
+        reflect_dom_object(
+            Box::new(DynamicModuleOwner::new_inherited(promise, id)),
+            global,
+        )
+    }
+}
+
+impl DynamicModuleOwnerMethods for DynamicModuleOwner {
+    // https://html.spec.whatwg.org/multipage/#integration-with-the-javascript-module-system:import()
+    fn Promise(&self) -> Rc<Promise> {
+        self.promise.clone()
+    }
+}

components/script/dom/mod.rs

@@ -295,6 +295,7 @@ pub mod domrectreadonly;
 pub mod domstringlist;
 pub mod domstringmap;
 pub mod domtokenlist;
+pub mod dynamicmoduleowner;
 pub mod element;
 pub mod errorevent;
 pub mod event;

components/script/dom/webidls/DynamicModuleOwner.webidl

@@ -0,0 +1,13 @@
+/* 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/. */
+
+/**
+ * This is defined for [`Dynamic Module`](https://html.spec.whatwg.org/multipage/#fetch-an-import()-module-script-graph)
+ * so that we can hold a traceable owner for those dynamic modules which don't hold a owner.
+ */
+
+[NoInterfaceObject, Exposed=Window]
+interface DynamicModuleOwner {
+  readonly attribute Promise<any> promise;
+};