Add size() and data() to SkAlignedSTStorage

Change-Id: I274e117215cf7c79c77a3b5b22e516528cfdc73a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/606903
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
2 files changed