Transform 3d-point-mapping-3.html to WPT

Test sometimes flakes due to slight differences in the anti aliasing of
the boxes. This was a good candidate to transform to a WPT test and stop
depending on png comparisons.

Bug: 424225631
Change-Id: I020f79ed8fdba856133166845a9d1070cb0f74ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6643005
Commit-Queue: Wangsong Jin <wangsongjin@microsoft.com>
Reviewed-by: Kevin Ellis <kevers@chromium.org>
Reviewed-by: Gaston Rodriguez <gastonr@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1475131}