LibWeb: Add stub implementation of CSS FontFace Web API

Author: https://github.com/ADKaster
Commit: 2c31d7dddc
Pull-request: https://github.com/SerenityOS/serenity/pull/24255
Issue: https://github.com/SerenityOS/serenity/issues/22014

Userland/Libraries/LibWeb/CSS/FontFace.cpp

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2024, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Heap/Heap.h>
+#include <LibJS/Runtime/Realm.h>
+#include <LibWeb/Bindings/FontFacePrototype.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/CSS/FontFace.h>
+#include <LibWeb/WebIDL/Promise.h>
+
+namespace Web::CSS {
+
+JS_DEFINE_ALLOCATOR(FontFace);
+
+JS::NonnullGCPtr<FontFace> FontFace::construct_impl(JS::Realm& realm, String family, FontFaceSource source, FontFaceDescriptors const& descriptors)
+{
+    return realm.heap().allocate<FontFace>(realm, realm, move(family), move(source), descriptors);
+}
+
+FontFace::FontFace(JS::Realm& realm, String, FontFaceSource, FontFaceDescriptors const&)
+    : Bindings::PlatformObject(realm)
+{
+}
+
+void FontFace::initialize(JS::Realm& realm)
+{
+    Base::initialize(realm);
+
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(FontFace);
+}
+
+// https://drafts.csswg.org/css-font-loading/#dom-fontface-load
+JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Promise>> FontFace::load()
+{
+    // FIXME: Do the steps
+    auto promise = WebIDL::create_rejected_promise(realm(), WebIDL::NotSupportedError::create(realm(), "FontFace::load is not yet implemented"_fly_string));
+    return verify_cast<JS::Promise>(*promise->promise());
+}
+
+}