Intent to ship: `PointerEvent.altitudeAngle` and `PointerEvent.azimuthAngle`

[Masayuki Nakano]

Summary: Implement and ship `PointerEvent.altitudeAngle` and
`PointerEvent.azimuthAngle`.

They are in the scope of Interop 2024 Events.

Pointer Events include two complementary sets of attributes to express
the orientation of a transducer relative to the X-Y plane: `tiltX` /
`tiltY` (introduced in the original Pointer Events specification), and
`azimuthAngle` / `altitudeAngle`. These sets of attributes can be
converted each other and we've already implemented `tiltX` and `tiltY`.
So, the new attributes will let web apps know the computed value from
`tiltX` and `tiltY` if a pointer event is fired to represent a user input.

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1656377

Spec:
<https://w3c.github.io/pointerevents/#dom-pointerevent-altitudeangle>,
<https://w3c.github.io/pointerevents/#dom-pointerevent-azimuthangle> and
<https://w3c.github.io/pointerevents/#converting-between-tiltx-tilty-and-altitudeangle-azimuthangle>

Other: Chrome has already implemented them, Safari has not done yet.

Web-platform-tests:
<https://wpt.fyi/results/pointerevents/pointerevent_tiltX_tiltY_to_azimuth_altitude.html?label=experimental&label=master&aligned
<https://wpt.fyi/results/pointerevents/pointerevent_tiltX_tiltY_to_azimuth_altitude.html?label=experimental&label=master&aligned>>

--
Masayuki Nakano <masa...@d-toybox.com>
Working on DOM, Events, editor and IME handling for Gecko