Add blendmode to GrRTC::drawTexture

This makes drawTexture handle blend modes with a fallback to be consistent
with drawTextureSet. Simple draws (other than non src-over) should be
faster now since they will skip the extra overhead of the GrTextureAdjuster.

It also refactors the GrPaint emulation of GrTextureOp into a function,
which will be reused in the general-purpose quad APIs.

Bug: skia:
Change-Id: Idad67ec749b82c6894df6ec2b57987130125b910
Reviewed-on: https://skia-review.googlesource.com/c/191360
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
5 files changed