Remove GP from drawstate, revision of invariant output for GP

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/c6bc58eded89b0c0a36b8e20e193c200f297a0da

Review URL: https://codereview.chromium.org/791743003
diff --git a/src/effects/gradients/SkGradientShader.cpp b/src/effects/gradients/SkGradientShader.cpp
index 0c14794..3b73eae 100644
--- a/src/effects/gradients/SkGradientShader.cpp
+++ b/src/effects/gradients/SkGradientShader.cpp
@@ -1158,9 +1158,9 @@
 
 void GrGradientEffect::onComputeInvariantOutput(GrInvariantOutput* inout) const {
     if (fIsOpaque) {
-        inout->mulByUnknownOpaqueColor();
+        inout->mulByUnknownOpaqueFourComponents();
     } else {
-        inout->mulByUnknownColor();
+        inout->mulByUnknownFourComponents();
     }
 }