A handful of updates to the initialization routine:
Remove XRDevice
Move supportsSession/requestSession to XR
Update supportsSession/requestSession to handle "mode" APIs
Support only "inline" and "immersive-vr" for now; plumbing already exists for the WebVR polyfilled device (leveraging "exclusive" and "outputContext"'d sessions)
A handful of updates to the initialization routine:
XRDevice
supportsSession
/requestSession
toXR
supportsSession
/requestSession
to handle "mode" APIsSee https://github.com/immersive-web/webxr-polyfill/issues/51 for more information on this effort, and development goals.