The technique for getting camera pose described here:
https://github.com/aframevr/aframe/blob/master/docs/components/camera.md#reading-world-position-or-rotation-of-the-camera
doesn't seem to work when in AR mode. (It used to work in all modes before A-Frame version 1.0) The reported world coordinates don't change with changes to device rotation (or translation, I think also), even though the camera's translation and rotation relative to the 3d scene elements clearly do. The technique for getting position and rotation of the camera (non-"world") on that page still works.

• A-Frame Version: 1.0 and higher
• Platform / Device: Chrome (w. sufficient config to support AR mode) on Android, Firefox-iOS (WebXR branch) on iOS

Maybe it's intentionally disabled in efforts to more fully support WebXR. Maybe AR mode implies that world coordinates are undefined?