script: Initial stubs for Credential Management API (#38839)

Stubs `Credential`, `CredentialContainer`, and `PasswordCredential` and
adds the credentials attribute to navigator.

Testing: WPT
Fixes: Partially #38788

---------

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

components/script/dom/credentialmanagement/passwordcredential.rs

@@ -0,0 +1,98 @@
+/* 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 dom_struct::dom_struct;
+use js::gc::HandleObject;
+use script_bindings::codegen::GenericBindings::PasswordCredentialBinding::PasswordCredentialData;
+use script_bindings::error::{Error, Fallible};
+use script_bindings::str::USVString;
+
+use crate::dom::bindings::codegen::Bindings::PasswordCredentialBinding::PasswordCredentialMethods;
+use crate::dom::bindings::codegen::DomTypeHolder::DomTypeHolder;
+use crate::dom::bindings::reflector::{reflect_dom_object, reflect_dom_object_with_proto};
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::credentialmanagement::credential::Credential;
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::htmlformelement::HTMLFormElement;
+use crate::dom::window::Window;
+use crate::script_runtime::CanGc;
+
+#[dom_struct]
+pub(crate) struct PasswordCredential {
+    credential: Credential,
+    origin: USVString,
+    password: USVString,
+}
+
+impl PasswordCredential {
+    fn new_inherited(id: USVString, origin: USVString, password: USVString) -> PasswordCredential {
+        PasswordCredential {
+            credential: Credential::new_inherited(id, "password".into()),
+            origin,
+            password,
+        }
+    }
+
+    #[expect(dead_code)]
+    pub(crate) fn new(
+        global: &GlobalScope,
+        id: USVString,
+        origin: USVString,
+        password: USVString,
+        can_gc: CanGc,
+    ) -> DomRoot<PasswordCredential> {
+        reflect_dom_object(
+            Box::new(PasswordCredential::new_inherited(id, origin, password)),
+            global,
+            can_gc,
+        )
+    }
+
+    pub(crate) fn new_with_proto(
+        global: &GlobalScope,
+        proto: Option<HandleObject>,
+        id: USVString,
+        origin: USVString,
+        password: USVString,
+        can_gc: CanGc,
+    ) -> DomRoot<PasswordCredential> {
+        reflect_dom_object_with_proto(
+            Box::new(PasswordCredential::new_inherited(id, origin, password)),
+            global,
+            proto,
+            can_gc,
+        )
+    }
+}
+
+impl PasswordCredentialMethods<DomTypeHolder> for PasswordCredential {
+    fn Password(&self) -> USVString {
+        self.password.clone()
+    }
+
+    fn Constructor(
+        _global: &Window,
+        _proto: Option<HandleObject>,
+        _can_gc: CanGc,
+        _form: &HTMLFormElement,
+    ) -> Fallible<DomRoot<PasswordCredential>> {
+        Err(Error::NotSupported)
+    }
+
+    fn Constructor_(
+        global: &Window,
+        proto: Option<HandleObject>,
+        can_gc: CanGc,
+        data: &PasswordCredentialData,
+    ) -> Fallible<DomRoot<PasswordCredential>> {
+        Ok(Self::new_with_proto(
+            global.as_global_scope(),
+            proto,
+            data.parent.id.clone(),
+            data.origin.clone(),
+            data.password.clone(),
+            can_gc,
+        ))
+    }
+}