Add matrix stack to SkAtlasTextTarget.

Makes SkAtlasTextRenderer::SDFVertex now has a 3 component position vector.

Change-Id: I7ec1a8068fb84388a82e1748d6e9d02820d55abd
Reviewed-on: https://skia-review.googlesource.com/84202
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
11 files changed