Remove fCacheKeys from SkImageFilter.

No public API changes.

Bug: skia:7666, skia:7887
Change-Id: I8ac4ec37dd3d0fcc050bc977db41439a8e18895f
Reviewed-on: https://skia-review.googlesource.com/125500
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Auto-Submit: Ben Wagner <benjaminwagner@google.com>
5 files changed