Howdy Piotr,
Somewhere, I believe, I read that In-App Web Browser used the default browser as the rendering engine. I also keep seeing references to Webview. Which is it?
If Webview I fear it will never be able to do exactly what I need — run in a window/panel in a 3D VR environment displaying WebVR content. Essentially that is what you say in the FAQ. But if In-App Web Browser is essentially a control skin for the “default browser” there may be hope and we could discuss options.