On Web, enable event propagation

[daxpedda]

This PR removes the code originally stopping events from being propagated from the canvas. The code inserting DeviceEvents before WindowEvents was also removed, de-duplicating a bunch of code.

The motivation here is the following:

• Reduce the side effects Winit has on the overall webpage that might or might not be desirable. Similar to Implement ResizeObserver #2859.
• Activating fullscreen requires a transient activation, which until now we detected by hijacking some already used events on the canvas. This isn't ideal because transient activation can happen anywhere on the page. Now that we have enabled event propagation, we can register events on the window to detect those activations.
• Remove more unnecessary code!