Hi,
I will look for it - the problem might be related to changing the view setting when in WebVR mode.
Currently the WebVR works that way - when entering VR mode, a backup of the current <view> setting will be made and then the <view> settings for VR will be set - BUT when now the <view> settings will be changed later, this can cause problems.
About devicecheck for VR - that's not possible - WebVR is not a device, it's a plugin that will be added later and it does VR-support detection at runtime.
Best regards,
Klaus