Use OffScreen canvas

[mnordine]

Might be a little perf boost to get canvas off the main thread.

https://developer.mozilla.org/en-US/docs/Web/API/OffscreenCanvas

[surma]

It's Chrome only and the devices that would benefit don't run a recent chrome. The remaining devices all run WebGL where we don't have performance problems. Once we have wide support for OSC, Id love to ship it tho