More SkColorSpaceXformer caching

  * apply(SkColorFilter*)
  * apply(SkImage*)

Change-Id: I9b55632edd73dbbc5edb8b5ca9bb5bead1131260
Reviewed-on: https://skia-review.googlesource.com/21736
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed