Implement ApplicationHandler::can_create|destroy_surfaces() (#3765)

src/platform_impl/web/event_loop/mod.rs

@@ -87,6 +87,7 @@ fn handle_event<A: ApplicationHandler>(app: &mut A, target: &RootActiveEventLoop
         Event::UserWakeUp => app.proxy_wake_up(target),
         Event::Suspended => app.suspended(target),
         Event::Resumed => app.resumed(target),
+        Event::CreateSurfaces => app.can_create_surfaces(target),
         Event::AboutToWait => app.about_to_wait(target),
         Event::LoopExiting => app.exiting(target),
         Event::MemoryWarning => app.memory_warning(target),