Bind handleAdd to AssetsView

src/asset_manager/view/AssetsView.js

@@ -59,7 +59,7 @@ module.exports = Backbone.View.extend({
     this.getAssetsEl().scrollTop = 0;
 
     if (handleAdd) {
-      handleAdd(url);
+      handleAdd.bind(this)(url);
     } else {
       this.options.globalCollection.add(url, { at: 0 });
     }