fold more in SkRasterPipelineBlitter

No change in behavior.  This just moves the responsibility for this optimization to the blitter (which knows what it's doing) rather than to compile_pipeline(), which sort of has to guess.

CQ_INCLUDE_TRYBOTS=skia.primary:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD

Change-Id: I93ad0ac896075deab995b865b188b42de637f0f7
Reviewed-on: https://skia-review.googlesource.com/5398
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Herb Derby <herb@google.com>
2 files changed