should fix any further errors for undefined render container callback

Change-Id: I1e9dc395629aba9143ae664ec8447edbf07b0cf5

gz3d/src/gzmultiview.js

@@ -37,6 +37,10 @@ GZ3D.MultiView.prototype.init = function()
         this.mainContainer.appendChild(this.gz3dScene.getDomElement());
     }
 
+    this.createRenderContainerCallback = function() {
+        return document.createElement('div');
+    };
+
     this.createMainUserView();
 };