Faster (conservative) IsAxisAligned

This is used to decide when we can keep the convex bit during
path.transform. This new version is much faster than the old,
but can return a false negative if there are multiple contours.

However, the caller now only calls this if the path is known to
be convex, so there should never be multiple contours.

This, along with

https://skia-review.googlesource.com/c/skia/+/359837

make path.transform() approx 2x faster

Bug: skia:11227
Change-Id: Ied7ca97d87b9224a3ecd9b77b22b823964809a52
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/359916
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
2 files changed