add Getter for canvasIIIF

src/plugins/VideosReferences.js

@@ -10,6 +10,9 @@ export const VideosReferences = {
   getCanvaSizeInformation(){
     return this.canvasSizeInformation
   },
+  getCanvasIIIF(){
+    return this.canvasIIIF;
+  },
   /** */
   set(windowId, ref) {
     this.refs[windowId] = ref;