Use self to get global context before window in getEventPriority.

[joewhatkins]

Prior to this change, this code would throw an error when run inside of a WebWorker, since window is not defined inside of webworkers.
This prevented us from using R3F inside of an offscreen canvas in a webworker.

See https://stackoverflow.com/questions/71587025/cant-use-offscreencanvas-with-react-three-fiber for an example.

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[CodyJasonBennett]

We also make use of requestAnimationFrame and devicePixelRatio.

A work-around would be to specify an integer rather than a range for dpr (overriding the default) and setting frameloop="never", but I'm not sure if this is what you want here.

[joewhatkins]

For our particular use case, this change alone suffices.

A work-around would be to specify an integer rather than a range for dpr (overriding the default) and setting frameloop="never", but I'm not sure if this is what you want here.

We specify an integer for DPR in our code, yeah, but our particular use case doesn't require us to set the frameloop.