Implement MallocSizeOf for most of WebXr. Mostly uncontroversal changes.
Of note:
- Implementation of size_of for euclid::RigidTransform
- Implementation of size_of for euclid::Vector3D
- Join is currently ignored as the type is very complicated.
Signed-off-by: Narfinger <Narfinger@users.noreply.github.com>
*Describe the changes that this pull request makes here. This will be
the commit message.*
Testing: Compilation is the test.
Signed-off-by: Narfinger <Narfinger@users.noreply.github.com>
