Vendor dependencies for 0.3.0 release

vendor/accesskit_winit/src/platform_impl/null.rs

@@ -0,0 +1,24 @@
+// Copyright 2022 The AccessKit Authors. All rights reserved.
+// Licensed under the Apache License, Version 2.0 (found in
+// the LICENSE-APACHE file).
+
+use accesskit::{ActionHandler, ActivationHandler, DeactivationHandler, TreeUpdate};
+use winit::{event::WindowEvent, event_loop::ActiveEventLoop, window::Window};
+
+pub struct Adapter;
+
+impl Adapter {
+    pub fn new(
+        _event_loop: &ActiveEventLoop,
+        _window: &Window,
+        _activation_handler: impl 'static + ActivationHandler,
+        _action_handler: impl 'static + ActionHandler,
+        _deactivation_handler: impl 'static + DeactivationHandler,
+    ) -> Self {
+        Self {}
+    }
+
+    pub fn update_if_active(&mut self, _updater: impl FnOnce() -> TreeUpdate) {}
+
+    pub fn process_event(&mut self, _window: &Window, _event: &WindowEvent) {}
+}