WebGLImageFilter is not compatible with Web Workers

[vladmandic]

WebGLImageFilter uses DOM methods to create canvas (e.g. document.createElement()) - and DOM is not available inside a web worker.

Should use OffscreenCanvas instead.

Which then leads to second problem, canvas and it's webgl context are initialized upon class creation and only resized upon subsequent access - but OffscreenCanvas cannot be resized, it has to be initialized with fixed size. Which means that initialization code should be modified so canvas is dynamically created (and it's context updated).

[vladmandic]

closing as no update from maintainer for over a year.