Make SkRRect work with axis aligned rotation transforms

This patch allows SkRRect::trasform() work with any axis aligned matrix
transform meaning it now works with a rotation of 90 or 270 degrees.

Adds relevant unit tests.

Bug: skia:8944
Change-Id: I63678ec0e3556c181517526de55d84666afeb681
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/205860
Reviewed-by: Robert Phillips <robertphillips@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
3 files changed