In the vr samples, handle rejection of getVRDisplays for the case when the API is available but WebVR is not supported

Author: SamiraAtMicrosoft

examples/js/vr/WebVR.js

@@ -191,7 +191,7 @@ var WEBVR = {
 
 					}
 
-				} );
+				} ).catch( showVRNotFound );
 
 			return button;