Implement Sk2f::Store2

Bug: skia:
Change-Id: Ifea5957458e5547ee428809d9599286e70f3f8f9
Reviewed-on: https://skia-review.googlesource.com/119860
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
4 files changed