How to display one iframe in a 3D scene in stereo mode WebVR? Three.js

How can I correctly display an iframe in a 3D scene in stereoscopic mode? The iframe will contain a game with canvas. I am using three.js Found a working example, but it loads 2 different iframes and the games work independently. That is, for each eye its own independent iframe works - Here is an example - You must insert a link.

I tried to solve the problem with another way. Having added the game, I transferred the current screenshot of the canvas (base64 for example) from the iframe through the PostMessage, displayed it in the intermediate canvas on the page and transferred this canvas as a texture to three.js. The circuit works but is very resource intensive. and I need to refine every game that ties my hands tightly.

Tell me please, maybe there is a simple solution for displaying one iframe in VR stereo mode?