Allow offscreen in thinengine

src/Engines/thinEngine.ts

@@ -503,7 +503,7 @@ export class ThinEngine {
      * @param options defines further options to be sent to the getContext() function
      * @param adaptToDeviceRatio defines whether to adapt to the device's viewport characteristics (default: false)
      */
-    constructor(canvasOrContext: Nullable<HTMLCanvasElement | WebGLRenderingContext | WebGL2RenderingContext>, antialias?: boolean, options?: EngineOptions, adaptToDeviceRatio: boolean = false) {
+    constructor(canvasOrContext: Nullable<HTMLCanvasElement | OffscreenCanvas | WebGLRenderingContext | WebGL2RenderingContext>, antialias?: boolean, options?: EngineOptions, adaptToDeviceRatio: boolean = false) {
 
         let canvas: Nullable<HTMLCanvasElement> = null;