In this CL:
- Modify modules/canvaskit/gpu.js to support the use of OffscreenCanvas.
- Add a CanvasKit demos.skia.org demo for CanvasKit in a Web Worker.
Change-Id: I8c26bd94f2aa5b3c09cf149b056b910b0e4cd602
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/304320
Reviewed-by: Elliot Evans <elliotevans@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Nathaniel Nifong <nifong@google.com>
Commit-Queue: Elliot Evans <elliotevans@google.com>
