* Keep track of what windows have requested redraw
Instead of using request_animation_frame and sending redraw request
events, just keep track of all windows that have asked for a redraw.
This doesn't handle dispatching the events
* Issue redraw events to windows that request it
* Cargo fmt
* Use actual numeric IDs to differentiate Windows
This is generally important to identifying which window should
recieve which event, but is also specifically crucial for fixing
RedrawRequested on web.
* Cargo fmt
