move some RRect methods into priv

also, return radii by value instead of reference, in possible prep for changing underlying representation

Bug: skia:7649
Change-Id: Iff42a49c53cc48171fc63462be366cc3500b2273
Reviewed-on: https://skia-review.googlesource.com/109385
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
16 files changed