Change was described in https://github.com/immersive-web/webxr/pull/357
The pointerMatrix in XRInputPose (which is actually already outdated and should have been targetRayMatrix) should be updated to an XRRay type. The XRRay continues to provide a transformation matrix that reports the same value as before, but additionally reports the ray origin and direction as DOMPointReadOnlys.
Comment 1 by btebbs@chromium.org
, Jul 30