Mouse events break if the first event received is a wheel event

If the very first mouse event received by a Qt Quick application is a wheel event, other events won't fire. This happens even if there are no components in the application that accept wheel events.

Steps to reproduce: Before the application launches, move the pointer to where the window will appear. Once it appears, don't move the pointer and scroll instead. Try clicking on MouseAreas after scrolling for any amount of time, and they won't respond. ListViews and MouseAreas will still respond to wheel events.

There's also some strange side effects to this issue on Windows specifically. Once everything gets stuck, move the pointer to where a ListView is and scroll. Then, move the pointer up or down, and the list view will start scrolling more in the direction that it was initially scrolled in by the wheel. This makes me think that move and click events are being interpreted as scroll events instead while this issue is in effect.

This issue doesn't occur on 5.11.2.