Canvas2D: fix bug with alignment used with designSize

src/Canvas2d/babylon.canvas2d.ts

@@ -1301,6 +1301,7 @@
                     scale = this._renderingSize.height / this._designSize.height;
                 }
                 this.size = this._designSize.clone();
+                this.actualSize = this._designSize.clone();
                 this.scale = scale;
             }