static registerSessionGrantedListener() {

		if ( typeof navigator !== 'undefined' && 'xr' in navigator ) {

			// WebXRViewer (based on Firefox) has a bug where addEventListener
			// throws a silent exception and aborts execution entirely.
			if ( /WebXRViewer\//i.test( navigator.userAgent ) ) return;

			navigator.xr.addEventListener( 'sessiongranted', () => {

				VRButton.xrSessionIsGranted = true;

			} );

		}

	}
Registers a `sessiongranted` event listener. When a session is granted, the {@link VRButton#xrSessionIsGranted}
flag will evaluate to `true`. This method is automatically called by the module itself so there
should be no need to use it on app level.