Revert "clamp gamut if needed in SkConvertPixels"

This reverts commit b8fef7c9869816c93a9e4fe9547d8ce4b82f2166.

Reason for revert: serialize-8888?

Original change's description:
> clamp gamut if needed in SkConvertPixels
> 
> We need to clamp here for all the same reasons we need to clamp when
> blitting.  I've centralized the clamp's implementation to help that.
> 
> I've allowed any --config to run this GM.  --config 565 was actually
> pointing out this problem by asserting, and now looks fine.
> 
> Change-Id: Icc066792fc53747b161302d200abdd8dc4669f7f
> Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
> Reviewed-on: https://skia-review.googlesource.com/158721
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Mike Klein <mtklein@google.com>

TBR=mtklein@google.com,brianosman@google.com

Change-Id: Id888656b313619ab2652a3387bdbc5208e192ec1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Reviewed-on: https://skia-review.googlesource.com/c/158980
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
5 files changed