How to use x3dom with polymer?

[Kelly St. John]

I'm not sure what I'm doing wrong.  I am comfortable with polymer, but have never used x3dom before.  I'm trying to load an external x3d file (the path to which is dynamic).  Here is the SO question and stripped-down code snippet:  http://stackoverflow.com/questions/35785680/how-to-use-x3dom-with-polymer

Any ideas what I might be doing wrong?  I don't see any reason why x3dom wouldn't play nice inside a polymer component.