Make SkColorSpaceXformer::apply(SkPaint) safe to call recursively

Before, we would stomp on the original paint in the recursive call.

This fixes 4 gbr-8888 gms.  Currently, this only affects loopers
and SkPaintImageFilter.

Bug: skia:6516
Change-Id: Ic47d637a912370c0a1ae8ef3282ad7d15d9902e3
Reviewed-on: https://skia-review.googlesource.com/14182
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
3 files changed